| Message ID | 20221118085030.121297-1-shaozhengchao@huawei.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] sctp: fix memory leak in sctp_stream_outq_migrate() | expand |
On Fri, Nov 18, 2022 at 3:48 AM Zhengchao Shao <shaozhengchao@huawei.com> wrote: > > When sctp_stream_outq_migrate() is called to release stream out resources, > the memory pointed to by prio_head in stream out is not released. > > The memory leak information is as follows: > unreferenced object 0xffff88801fe79f80 (size 64): > comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) > hex dump (first 32 bytes): > 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ > 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ > backtrace: > [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60 > [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770 > [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0 > [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30 > [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0 > [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0 > [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120 > [<ffffffff8755446a>] __sys_sendto+0x23a/0x340 > [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0 > [<ffffffff89978b49>] do_syscall_64+0x39/0xb0 > [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") > Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com > Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> > --- > net/sctp/stream.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/net/sctp/stream.c b/net/sctp/stream.c > index ef9fceadef8d..a17dc368876f 100644 > --- a/net/sctp/stream.c > +++ b/net/sctp/stream.c > @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > * sctp_stream_update will swap ->out pointers. > */ > for (i = 0; i < outcnt; i++) { > + if (SCTP_SO(new, i)->ext) > + kfree(SCTP_SO(new, i)->ext->prio_head); > + > kfree(SCTP_SO(new, i)->ext); > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > SCTP_SO(stream, i)->ext = NULL; > @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > } > > for (i = outcnt; i < stream->outcnt; i++) { > + if (SCTP_SO(stream, i)->ext) > + kfree(SCTP_SO(stream, i)->ext->prio_head); > + > kfree(SCTP_SO(stream, i)->ext); > SCTP_SO(stream, i)->ext = NULL; > } > -- > 2.17.1 > This is not a proper fix: 1. you shouldn't access "prio_head" outside stream_sched_prio.c. 2. the prio_head you freed might be used by other out streams, freeing it unconditionally would cause either a double free or use after free. I'm afraid we have to add a ".free_sid" in sctp_sched_ops, and implement it for sctp_sched_prio, like: +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid) +{ + struct sctp_stream_priorities *prio = SCTP_SO(stream, sid)->ext->prio_head; + int i; + + if (!prio) + return; + + SCTP_SO(stream, sid)->ext->prio_head = NULL; + for (i = 0; i < stream->outcnt; i++) { + if (SCTP_SO(stream, i)->ext && + SCTP_SO(stream, i)->ext->prio_head == prio) + return; + } + kfree(prio); +} + static void sctp_sched_prio_free(struct sctp_stream *stream) { struct sctp_stream_priorities *prio, *n; @@ -323,6 +340,7 @@ static struct sctp_sched_ops sctp_sched_prio = { .get = sctp_sched_prio_get, .init = sctp_sched_prio_init, .init_sid = sctp_sched_prio_init_sid, + .free_sid = sctp_sched_prio_free_sid, .free = sctp_sched_prio_free, .enqueue = sctp_sched_prio_enqueue, .dequeue = sctp_sched_prio_dequeue, then call it in sctp_stream_outq_migrate(), like: +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid) +{ + struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream); + + sched->free_sid(stream, sid); + kfree(SCTP_SO(stream, sid)->ext); + SCTP_SO(stream, sid)->ext = NULL; +} + /* Migrates chunks from stream queues to new stream queues if needed, * but not across associations. Also, removes those chunks to streams * higher than the new max. @@ -70,16 +79,14 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, * sctp_stream_update will swap ->out pointers. */ for (i = 0; i < outcnt; i++) { - kfree(SCTP_SO(new, i)->ext); + sctp_stream_free_ext(new, i); SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; SCTP_SO(stream, i)->ext = NULL; } } - for (i = outcnt; i < stream->outcnt; i++) { - kfree(SCTP_SO(stream, i)->ext); - SCTP_SO(stream, i)->ext = NULL; - } + for (i = outcnt; i < stream->outcnt; i++) + sctp_stream_free_ext(new, i); } Marcelo, do you see a better solution? Thanks.
On Fri, Nov 18, 2022 at 10:15:50PM -0500, Xin Long wrote: > On Fri, Nov 18, 2022 at 3:48 AM Zhengchao Shao <shaozhengchao@huawei.com> wrote: > > > > When sctp_stream_outq_migrate() is called to release stream out resources, > > the memory pointed to by prio_head in stream out is not released. > > > > The memory leak information is as follows: > > unreferenced object 0xffff88801fe79f80 (size 64): > > comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) > > hex dump (first 32 bytes): > > 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ > > 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ > > backtrace: > > [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60 > > [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770 > > [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0 > > [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30 > > [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0 > > [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0 > > [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120 > > [<ffffffff8755446a>] __sys_sendto+0x23a/0x340 > > [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0 > > [<ffffffff89978b49>] do_syscall_64+0x39/0xb0 > > [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") > > Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com > > Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> > > --- > > net/sctp/stream.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/net/sctp/stream.c b/net/sctp/stream.c > > index ef9fceadef8d..a17dc368876f 100644 > > --- a/net/sctp/stream.c > > +++ b/net/sctp/stream.c > > @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > * sctp_stream_update will swap ->out pointers. > > */ > > for (i = 0; i < outcnt; i++) { > > + if (SCTP_SO(new, i)->ext) > > + kfree(SCTP_SO(new, i)->ext->prio_head); > > + > > kfree(SCTP_SO(new, i)->ext); > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > SCTP_SO(stream, i)->ext = NULL; > > @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > } > > > > for (i = outcnt; i < stream->outcnt; i++) { > > + if (SCTP_SO(stream, i)->ext) > > + kfree(SCTP_SO(stream, i)->ext->prio_head); > > + > > kfree(SCTP_SO(stream, i)->ext); > > SCTP_SO(stream, i)->ext = NULL; > > } > > -- > > 2.17.1 > > > This is not a proper fix: > 1. you shouldn't access "prio_head" outside stream_sched_prio.c. > 2. the prio_head you freed might be used by other out streams, freeing > it unconditionally would cause either a double free or use after free. > > I'm afraid we have to add a ".free_sid" in sctp_sched_ops, and > implement it for sctp_sched_prio, like: > > +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid) > +{ > + struct sctp_stream_priorities *prio = SCTP_SO(stream, > sid)->ext->prio_head; > + int i; > + > + if (!prio) > + return; > + > + SCTP_SO(stream, sid)->ext->prio_head = NULL; > + for (i = 0; i < stream->outcnt; i++) { Instead of checking all streams, the for() can/should be replaced by (from sctp_sched_prio_free): if (!list_empty(&prio->prio_sched)) return; > + if (SCTP_SO(stream, i)->ext && > + SCTP_SO(stream, i)->ext->prio_head == prio) > + return; > + } > + kfree(prio); > +} > + > static void sctp_sched_prio_free(struct sctp_stream *stream) > { > struct sctp_stream_priorities *prio, *n; > @@ -323,6 +340,7 @@ static struct sctp_sched_ops sctp_sched_prio = { > .get = sctp_sched_prio_get, > .init = sctp_sched_prio_init, > .init_sid = sctp_sched_prio_init_sid, > + .free_sid = sctp_sched_prio_free_sid, > .free = sctp_sched_prio_free, > .enqueue = sctp_sched_prio_enqueue, > .dequeue = sctp_sched_prio_dequeue, > > then call it in sctp_stream_outq_migrate(), like: > > +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid) > +{ > + struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream); > + > + sched->free_sid(stream, sid); > + kfree(SCTP_SO(stream, sid)->ext); > + SCTP_SO(stream, sid)->ext = NULL; > +} > + > /* Migrates chunks from stream queues to new stream queues if needed, > * but not across associations. Also, removes those chunks to streams > * higher than the new max. > @@ -70,16 +79,14 @@ static void sctp_stream_outq_migrate(struct > sctp_stream *stream, > * sctp_stream_update will swap ->out pointers. > */ > for (i = 0; i < outcnt; i++) { > - kfree(SCTP_SO(new, i)->ext); > + sctp_stream_free_ext(new, i); > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > SCTP_SO(stream, i)->ext = NULL; > } > } > > - for (i = outcnt; i < stream->outcnt; i++) { > - kfree(SCTP_SO(stream, i)->ext); > - SCTP_SO(stream, i)->ext = NULL; > - } > + for (i = outcnt; i < stream->outcnt; i++) > + sctp_stream_free_ext(new, i); > } > > Marcelo, do you see a better solution? No. Your suggestion is the best I could think of too. Another approach would be to expose sched->free and do all the freeing at once, like sctp_stream_free() does. But the above is looks cleaner and makes it evident that freeing 'ext' is not trivial. With the proposal above, sctp_sched_prio_free() becomes an optimization, if we can call it that. With the for/if replacement above, not even that, and should be removed. Including sctp_sched_ops 'free' pointer. sctp_stream_free() then should be updated to use the new sctp_stream_free_ext() instead, instead of mangling it directly. Makes sense? Thanks, Marcelo
On Tue, Nov 22, 2022 at 6:35 PM Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> wrote: > > On Fri, Nov 18, 2022 at 10:15:50PM -0500, Xin Long wrote: > > On Fri, Nov 18, 2022 at 3:48 AM Zhengchao Shao <shaozhengchao@huawei.com> wrote: > > > > > > When sctp_stream_outq_migrate() is called to release stream out resources, > > > the memory pointed to by prio_head in stream out is not released. > > > > > > The memory leak information is as follows: > > > unreferenced object 0xffff88801fe79f80 (size 64): > > > comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) > > > hex dump (first 32 bytes): > > > 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ > > > 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ > > > backtrace: > > > [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60 > > > [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770 > > > [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0 > > > [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30 > > > [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0 > > > [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0 > > > [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120 > > > [<ffffffff8755446a>] __sys_sendto+0x23a/0x340 > > > [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0 > > > [<ffffffff89978b49>] do_syscall_64+0x39/0xb0 > > > [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > > > Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") > > > Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com > > > Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> > > > --- > > > net/sctp/stream.c | 6 ++++++ > > > 1 file changed, 6 insertions(+) > > > > > > diff --git a/net/sctp/stream.c b/net/sctp/stream.c > > > index ef9fceadef8d..a17dc368876f 100644 > > > --- a/net/sctp/stream.c > > > +++ b/net/sctp/stream.c > > > @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > * sctp_stream_update will swap ->out pointers. > > > */ > > > for (i = 0; i < outcnt; i++) { > > > + if (SCTP_SO(new, i)->ext) > > > + kfree(SCTP_SO(new, i)->ext->prio_head); > > > + > > > kfree(SCTP_SO(new, i)->ext); > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > SCTP_SO(stream, i)->ext = NULL; > > > @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > } > > > > > > for (i = outcnt; i < stream->outcnt; i++) { > > > + if (SCTP_SO(stream, i)->ext) > > > + kfree(SCTP_SO(stream, i)->ext->prio_head); > > > + > > > kfree(SCTP_SO(stream, i)->ext); > > > SCTP_SO(stream, i)->ext = NULL; > > > } > > > -- > > > 2.17.1 > > > > > This is not a proper fix: > > 1. you shouldn't access "prio_head" outside stream_sched_prio.c. > > 2. the prio_head you freed might be used by other out streams, freeing > > it unconditionally would cause either a double free or use after free. > > > > I'm afraid we have to add a ".free_sid" in sctp_sched_ops, and > > implement it for sctp_sched_prio, like: > > > > +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid) > > +{ > > + struct sctp_stream_priorities *prio = SCTP_SO(stream, > > sid)->ext->prio_head; > > + int i; > > + > > + if (!prio) > > + return; > > + > > + SCTP_SO(stream, sid)->ext->prio_head = NULL; > > + for (i = 0; i < stream->outcnt; i++) { > > Instead of checking all streams, the for() can/should be replaced by > (from sctp_sched_prio_free): > if (!list_empty(&prio->prio_sched)) > return; sctp_stream_outq_migrate() is called after unsched_all() for "stream", list_empty(prio_sched) is expected to be true. Note that kfree(SCTP_SO(new, i)->ext) shouldn't have the reported problem, as at that moment, the "new" stream hasn't been set stream_sched yet. It means there's only one place that needs to call free_sid in sctp_stream_outq_migrate(). (Maybe Zhengchao can help us confirm this?) > > > + if (SCTP_SO(stream, i)->ext && > > + SCTP_SO(stream, i)->ext->prio_head == prio) > > + return; > > + } > > + kfree(prio); > > +} > > + > > static void sctp_sched_prio_free(struct sctp_stream *stream) > > { > > struct sctp_stream_priorities *prio, *n; > > @@ -323,6 +340,7 @@ static struct sctp_sched_ops sctp_sched_prio = { > > .get = sctp_sched_prio_get, > > .init = sctp_sched_prio_init, > > .init_sid = sctp_sched_prio_init_sid, > > + .free_sid = sctp_sched_prio_free_sid, > > .free = sctp_sched_prio_free, > > .enqueue = sctp_sched_prio_enqueue, > > .dequeue = sctp_sched_prio_dequeue, > > > > then call it in sctp_stream_outq_migrate(), like: > > > > +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid) > > +{ > > + struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream); > > + > > + sched->free_sid(stream, sid); > > + kfree(SCTP_SO(stream, sid)->ext); > > + SCTP_SO(stream, sid)->ext = NULL; > > +} > > + > > /* Migrates chunks from stream queues to new stream queues if needed, > > * but not across associations. Also, removes those chunks to streams > > * higher than the new max. > > @@ -70,16 +79,14 @@ static void sctp_stream_outq_migrate(struct > > sctp_stream *stream, > > * sctp_stream_update will swap ->out pointers. > > */ > > for (i = 0; i < outcnt; i++) { > > - kfree(SCTP_SO(new, i)->ext); > > + sctp_stream_free_ext(new, i); > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > SCTP_SO(stream, i)->ext = NULL; > > } > > } > > > > - for (i = outcnt; i < stream->outcnt; i++) { > > - kfree(SCTP_SO(stream, i)->ext); > > - SCTP_SO(stream, i)->ext = NULL; > > - } > > + for (i = outcnt; i < stream->outcnt; i++) > > + sctp_stream_free_ext(new, i); > > } > > > > Marcelo, do you see a better solution? > > No. Your suggestion is the best I could think of too. > > Another approach would be to expose sched->free and do all the freeing > at once, like sctp_stream_free() does. But the above is looks cleaner > and makes it evident that freeing 'ext' is not trivial. > > With the proposal above, sctp_sched_prio_free() becomes an > optimization, if we can call it that. With the for/if replacement > above, not even that, and should be removed. Including sctp_sched_ops > 'free' pointer. Or we extract the common code to another function, like sctp_sched_prio_free_head(stream, prio), and pass prio as NULL in sctp_sched_prio_free() for freeing all. > > sctp_stream_free() then should be updated to use the new > sctp_stream_free_ext() instead, instead of mangling it directly. I thought about this, but there is ".free", which is more efficient to free all prio than calling ".free_sid" outcnt times. I may move free_sid() out of sctp_stream_free_ext(), then in sctp_stream_free() we can call sctp_stream_free_ext() without calling free_sid(), or just remove sctp_stream_free_ext(). Thanks. > > Makes sense? > > Thanks, > Marcelo
On Wed, Nov 23, 2022 at 12:20:44PM -0500, Xin Long wrote: > On Tue, Nov 22, 2022 at 6:35 PM Marcelo Ricardo Leitner > <marcelo.leitner@gmail.com> wrote: > > > > On Fri, Nov 18, 2022 at 10:15:50PM -0500, Xin Long wrote: > > > On Fri, Nov 18, 2022 at 3:48 AM Zhengchao Shao <shaozhengchao@huawei.com> wrote: > > > > > > > > When sctp_stream_outq_migrate() is called to release stream out resources, > > > > the memory pointed to by prio_head in stream out is not released. > > > > > > > > The memory leak information is as follows: > > > > unreferenced object 0xffff88801fe79f80 (size 64): > > > > comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) > > > > hex dump (first 32 bytes): > > > > 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ > > > > 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ > > > > backtrace: > > > > [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60 > > > > [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770 > > > > [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0 > > > > [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30 > > > > [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0 > > > > [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0 > > > > [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120 > > > > [<ffffffff8755446a>] __sys_sendto+0x23a/0x340 > > > > [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0 > > > > [<ffffffff89978b49>] do_syscall_64+0x39/0xb0 > > > > [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > > > > > Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") > > > > Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com > > > > Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> > > > > --- > > > > net/sctp/stream.c | 6 ++++++ > > > > 1 file changed, 6 insertions(+) > > > > > > > > diff --git a/net/sctp/stream.c b/net/sctp/stream.c > > > > index ef9fceadef8d..a17dc368876f 100644 > > > > --- a/net/sctp/stream.c > > > > +++ b/net/sctp/stream.c > > > > @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > * sctp_stream_update will swap ->out pointers. > > > > */ > > > > for (i = 0; i < outcnt; i++) { > > > > + if (SCTP_SO(new, i)->ext) > > > > + kfree(SCTP_SO(new, i)->ext->prio_head); > > > > + > > > > kfree(SCTP_SO(new, i)->ext); > > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > > SCTP_SO(stream, i)->ext = NULL; > > > > @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > } > > > > > > > > for (i = outcnt; i < stream->outcnt; i++) { > > > > + if (SCTP_SO(stream, i)->ext) > > > > + kfree(SCTP_SO(stream, i)->ext->prio_head); > > > > + > > > > kfree(SCTP_SO(stream, i)->ext); > > > > SCTP_SO(stream, i)->ext = NULL; > > > > } > > > > -- > > > > 2.17.1 > > > > > > > This is not a proper fix: > > > 1. you shouldn't access "prio_head" outside stream_sched_prio.c. > > > 2. the prio_head you freed might be used by other out streams, freeing > > > it unconditionally would cause either a double free or use after free. > > > > > > I'm afraid we have to add a ".free_sid" in sctp_sched_ops, and > > > implement it for sctp_sched_prio, like: > > > > > > +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid) > > > +{ > > > + struct sctp_stream_priorities *prio = SCTP_SO(stream, > > > sid)->ext->prio_head; > > > + int i; > > > + > > > + if (!prio) > > > + return; > > > + > > > + SCTP_SO(stream, sid)->ext->prio_head = NULL; > > > + for (i = 0; i < stream->outcnt; i++) { > > > > Instead of checking all streams, the for() can/should be replaced by > > (from sctp_sched_prio_free): > > if (!list_empty(&prio->prio_sched)) > > return; > sctp_stream_outq_migrate() is called after unsched_all() for "stream", > list_empty(prio_sched) is expected to be true. Good point. Am I missing something or the 'prio_head == prio' below would always be false then as well? Anyhow, as this is moving to something that can potentially be called from other places afterwards, keeping the check doesn't hurt. > > Note that kfree(SCTP_SO(new, i)->ext) shouldn't have the reported > problem, as at that moment, the "new" stream hasn't been set > stream_sched yet. It means there's only one place that needs to > call free_sid in sctp_stream_outq_migrate(). > (Maybe Zhengchao can help us confirm this?) That's the case in Tetsuo's patch (earlier today) as well. Yet, if we have an official way to free a stream, if it's not error handling during initialization, it should use it. > > > > > > + if (SCTP_SO(stream, i)->ext && > > > + SCTP_SO(stream, i)->ext->prio_head == prio) > > > + return; > > > + } > > > + kfree(prio); > > > +} > > > + > > > static void sctp_sched_prio_free(struct sctp_stream *stream) > > > { > > > struct sctp_stream_priorities *prio, *n; > > > @@ -323,6 +340,7 @@ static struct sctp_sched_ops sctp_sched_prio = { > > > .get = sctp_sched_prio_get, > > > .init = sctp_sched_prio_init, > > > .init_sid = sctp_sched_prio_init_sid, > > > + .free_sid = sctp_sched_prio_free_sid, > > > .free = sctp_sched_prio_free, > > > .enqueue = sctp_sched_prio_enqueue, > > > .dequeue = sctp_sched_prio_dequeue, > > > > > > then call it in sctp_stream_outq_migrate(), like: > > > > > > +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid) > > > +{ > > > + struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream); > > > + > > > + sched->free_sid(stream, sid); > > > + kfree(SCTP_SO(stream, sid)->ext); > > > + SCTP_SO(stream, sid)->ext = NULL; > > > +} > > > + > > > /* Migrates chunks from stream queues to new stream queues if needed, > > > * but not across associations. Also, removes those chunks to streams > > > * higher than the new max. > > > @@ -70,16 +79,14 @@ static void sctp_stream_outq_migrate(struct > > > sctp_stream *stream, > > > * sctp_stream_update will swap ->out pointers. > > > */ > > > for (i = 0; i < outcnt; i++) { > > > - kfree(SCTP_SO(new, i)->ext); > > > + sctp_stream_free_ext(new, i); > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > SCTP_SO(stream, i)->ext = NULL; > > > } > > > } > > > > > > - for (i = outcnt; i < stream->outcnt; i++) { > > > - kfree(SCTP_SO(stream, i)->ext); > > > - SCTP_SO(stream, i)->ext = NULL; > > > - } > > > + for (i = outcnt; i < stream->outcnt; i++) > > > + sctp_stream_free_ext(new, i); > > > } > > > > > > Marcelo, do you see a better solution? > > > > No. Your suggestion is the best I could think of too. > > > > Another approach would be to expose sched->free and do all the freeing > > at once, like sctp_stream_free() does. But the above is looks cleaner > > and makes it evident that freeing 'ext' is not trivial. > > > > With the proposal above, sctp_sched_prio_free() becomes an > > optimization, if we can call it that. With the for/if replacement > > above, not even that, and should be removed. Including sctp_sched_ops > > 'free' pointer. > Or we extract the common code to another function, like > sctp_sched_prio_free_head(stream, prio), and pass prio as > NULL in sctp_sched_prio_free() for freeing all. > > > > > sctp_stream_free() then should be updated to use the new > > sctp_stream_free_ext() instead, instead of mangling it directly. > I thought about this, but there is ".free", which is more efficient > to free all prio than calling ".free_sid" outcnt times. How much more efficient, just by avoiding retpoline stuff on the indirect functional call or something else? > > I may move free_sid() out of sctp_stream_free_ext(), then in > sctp_stream_free() we can call sctp_stream_free_ext() without > calling free_sid(), or just remove sctp_stream_free_ext(). It's easier to maintain it if we have symmetric paths for initializing and for freeing it and less special cases. We already have sctp_stream_init_ext(), so having sctp_stream_free_ext() is not off. I'm happy to review any patch that also updates sctp_stream_free(), one way or another. > > Thanks. > > > > > Makes sense? > > > > Thanks, > > Marcelo
( On Wed, Nov 23, 2022 at 1:10 PM Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> wrote: > > On Wed, Nov 23, 2022 at 12:20:44PM -0500, Xin Long wrote: > > On Tue, Nov 22, 2022 at 6:35 PM Marcelo Ricardo Leitner > > <marcelo.leitner@gmail.com> wrote: > > > > > > On Fri, Nov 18, 2022 at 10:15:50PM -0500, Xin Long wrote: > > > > On Fri, Nov 18, 2022 at 3:48 AM Zhengchao Shao <shaozhengchao@huawei.com> wrote: > > > > > > > > > > When sctp_stream_outq_migrate() is called to release stream out resources, > > > > > the memory pointed to by prio_head in stream out is not released. > > > > > > > > > > The memory leak information is as follows: > > > > > unreferenced object 0xffff88801fe79f80 (size 64): > > > > > comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) > > > > > hex dump (first 32 bytes): > > > > > 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ > > > > > 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ > > > > > backtrace: > > > > > [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60 > > > > > [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770 > > > > > [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0 > > > > > [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30 > > > > > [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0 > > > > > [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0 > > > > > [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120 > > > > > [<ffffffff8755446a>] __sys_sendto+0x23a/0x340 > > > > > [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0 > > > > > [<ffffffff89978b49>] do_syscall_64+0x39/0xb0 > > > > > [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > > > > > > > Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") > > > > > Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com > > > > > Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> > > > > > --- > > > > > net/sctp/stream.c | 6 ++++++ > > > > > 1 file changed, 6 insertions(+) > > > > > > > > > > diff --git a/net/sctp/stream.c b/net/sctp/stream.c > > > > > index ef9fceadef8d..a17dc368876f 100644 > > > > > --- a/net/sctp/stream.c > > > > > +++ b/net/sctp/stream.c > > > > > @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > > * sctp_stream_update will swap ->out pointers. > > > > > */ > > > > > for (i = 0; i < outcnt; i++) { > > > > > + if (SCTP_SO(new, i)->ext) > > > > > + kfree(SCTP_SO(new, i)->ext->prio_head); > > > > > + > > > > > kfree(SCTP_SO(new, i)->ext); > > > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > > } > > > > > > > > > > for (i = outcnt; i < stream->outcnt; i++) { > > > > > + if (SCTP_SO(stream, i)->ext) > > > > > + kfree(SCTP_SO(stream, i)->ext->prio_head); > > > > > + > > > > > kfree(SCTP_SO(stream, i)->ext); > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > } > > > > > -- > > > > > 2.17.1 > > > > > > > > > This is not a proper fix: > > > > 1. you shouldn't access "prio_head" outside stream_sched_prio.c. > > > > 2. the prio_head you freed might be used by other out streams, freeing > > > > it unconditionally would cause either a double free or use after free. > > > > > > > > I'm afraid we have to add a ".free_sid" in sctp_sched_ops, and > > > > implement it for sctp_sched_prio, like: > > > > > > > > +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid) > > > > +{ > > > > + struct sctp_stream_priorities *prio = SCTP_SO(stream, > > > > sid)->ext->prio_head; > > > > + int i; > > > > + > > > > + if (!prio) > > > > + return; > > > > + > > > > + SCTP_SO(stream, sid)->ext->prio_head = NULL; > > > > + for (i = 0; i < stream->outcnt; i++) { > > > > > > Instead of checking all streams, the for() can/should be replaced by > > > (from sctp_sched_prio_free): > > > if (!list_empty(&prio->prio_sched)) > > > return; > > sctp_stream_outq_migrate() is called after unsched_all() for "stream", > > list_empty(prio_sched) is expected to be true. > > Good point. Am I missing something or the 'prio_head == prio' below > would always be false then as well? > > Anyhow, as this is moving to something that can potentially be called > from other places afterwards, keeping the check doesn't hurt. > > > > > Note that kfree(SCTP_SO(new, i)->ext) shouldn't have the reported > > problem, as at that moment, the "new" stream hasn't been set > > stream_sched yet. It means there's only one place that needs to > > call free_sid in sctp_stream_outq_migrate(). > > (Maybe Zhengchao can help us confirm this?) > > That's the case in Tetsuo's patch (earlier today) as well. Yet, if we > have an official way to free a stream, if it's not error handling > during initialization, it should use it. right. > > > > > > > > > > + if (SCTP_SO(stream, i)->ext && > > > > + SCTP_SO(stream, i)->ext->prio_head == prio) > > > > + return; > > > > + } > > > > + kfree(prio); > > > > +} > > > > + > > > > static void sctp_sched_prio_free(struct sctp_stream *stream) > > > > { > > > > struct sctp_stream_priorities *prio, *n; > > > > @@ -323,6 +340,7 @@ static struct sctp_sched_ops sctp_sched_prio = { > > > > .get = sctp_sched_prio_get, > > > > .init = sctp_sched_prio_init, > > > > .init_sid = sctp_sched_prio_init_sid, > > > > + .free_sid = sctp_sched_prio_free_sid, > > > > .free = sctp_sched_prio_free, > > > > .enqueue = sctp_sched_prio_enqueue, > > > > .dequeue = sctp_sched_prio_dequeue, > > > > > > > > then call it in sctp_stream_outq_migrate(), like: > > > > > > > > +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid) > > > > +{ > > > > + struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream); > > > > + > > > > + sched->free_sid(stream, sid); > > > > + kfree(SCTP_SO(stream, sid)->ext); > > > > + SCTP_SO(stream, sid)->ext = NULL; > > > > +} > > > > + > > > > /* Migrates chunks from stream queues to new stream queues if needed, > > > > * but not across associations. Also, removes those chunks to streams > > > > * higher than the new max. > > > > @@ -70,16 +79,14 @@ static void sctp_stream_outq_migrate(struct > > > > sctp_stream *stream, > > > > * sctp_stream_update will swap ->out pointers. > > > > */ > > > > for (i = 0; i < outcnt; i++) { > > > > - kfree(SCTP_SO(new, i)->ext); > > > > + sctp_stream_free_ext(new, i); > > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > > SCTP_SO(stream, i)->ext = NULL; > > > > } > > > > } > > > > > > > > - for (i = outcnt; i < stream->outcnt; i++) { > > > > - kfree(SCTP_SO(stream, i)->ext); > > > > - SCTP_SO(stream, i)->ext = NULL; > > > > - } > > > > + for (i = outcnt; i < stream->outcnt; i++) > > > > + sctp_stream_free_ext(new, i); > > > > } > > > > > > > > Marcelo, do you see a better solution? > > > > > > No. Your suggestion is the best I could think of too. > > > > > > Another approach would be to expose sched->free and do all the freeing > > > at once, like sctp_stream_free() does. But the above is looks cleaner > > > and makes it evident that freeing 'ext' is not trivial. > > > > > > With the proposal above, sctp_sched_prio_free() becomes an > > > optimization, if we can call it that. With the for/if replacement > > > above, not even that, and should be removed. Including sctp_sched_ops > > > 'free' pointer. > > Or we extract the common code to another function, like > > sctp_sched_prio_free_head(stream, prio), and pass prio as > > NULL in sctp_sched_prio_free() for freeing all. > > > > > > > > sctp_stream_free() then should be updated to use the new > > > sctp_stream_free_ext() instead, instead of mangling it directly. > > I thought about this, but there is ".free", which is more efficient > > to free all prio than calling ".free_sid" outcnt times. > > How much more efficient, just by avoiding retpoline stuff on the > indirect functional call or something else? in sctp_stream_free(): .free() will be called one time to free all prios while .free_sid will be called in a loop to free all prios: for (i = 0; i < stream->outcnt; i++) .free_sid(stream, i); inside either() .free or . free_sid() there is another loop: for (i = 0; i < stream->outcnt; i++) ... That's why I said using .free() in sctp_stream_free() will be more efficient. > > > > > I may move free_sid() out of sctp_stream_free_ext(), then in > > sctp_stream_free() we can call sctp_stream_free_ext() without > > calling free_sid(), or just remove sctp_stream_free_ext(). > > It's easier to maintain it if we have symmetric paths for initializing > and for freeing it and less special cases. We already have > sctp_stream_init_ext(), so having sctp_stream_free_ext() is not off. didn't notice init_sid in sctp_stream_init_ext(), it makes sense to have free_sid in sctp_stream_free_ext(). Thanks. > > I'm happy to review any patch that also updates sctp_stream_free(), > one way or another. > > > > > Thanks. > > > > > > > > Makes sense? > > > > > > Thanks, > > > Marcelo
On Wed, Nov 23, 2022 at 1:30 PM Xin Long <lucien.xin@gmail.com> wrote: > > ( > > On Wed, Nov 23, 2022 at 1:10 PM Marcelo Ricardo Leitner > <marcelo.leitner@gmail.com> wrote: > > > > On Wed, Nov 23, 2022 at 12:20:44PM -0500, Xin Long wrote: > > > On Tue, Nov 22, 2022 at 6:35 PM Marcelo Ricardo Leitner > > > <marcelo.leitner@gmail.com> wrote: > > > > > > > > On Fri, Nov 18, 2022 at 10:15:50PM -0500, Xin Long wrote: > > > > > On Fri, Nov 18, 2022 at 3:48 AM Zhengchao Shao <shaozhengchao@huawei.com> wrote: > > > > > > > > > > > > When sctp_stream_outq_migrate() is called to release stream out resources, > > > > > > the memory pointed to by prio_head in stream out is not released. > > > > > > > > > > > > The memory leak information is as follows: > > > > > > unreferenced object 0xffff88801fe79f80 (size 64): > > > > > > comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) > > > > > > hex dump (first 32 bytes): > > > > > > 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ > > > > > > 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ > > > > > > backtrace: > > > > > > [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60 > > > > > > [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770 > > > > > > [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0 > > > > > > [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30 > > > > > > [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0 > > > > > > [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0 > > > > > > [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120 > > > > > > [<ffffffff8755446a>] __sys_sendto+0x23a/0x340 > > > > > > [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0 > > > > > > [<ffffffff89978b49>] do_syscall_64+0x39/0xb0 > > > > > > [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > > > > > > > > > Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") > > > > > > Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com > > > > > > Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> > > > > > > --- > > > > > > net/sctp/stream.c | 6 ++++++ > > > > > > 1 file changed, 6 insertions(+) > > > > > > > > > > > > diff --git a/net/sctp/stream.c b/net/sctp/stream.c > > > > > > index ef9fceadef8d..a17dc368876f 100644 > > > > > > --- a/net/sctp/stream.c > > > > > > +++ b/net/sctp/stream.c > > > > > > @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > > > * sctp_stream_update will swap ->out pointers. > > > > > > */ > > > > > > for (i = 0; i < outcnt; i++) { > > > > > > + if (SCTP_SO(new, i)->ext) > > > > > > + kfree(SCTP_SO(new, i)->ext->prio_head); > > > > > > + > > > > > > kfree(SCTP_SO(new, i)->ext); > > > > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > > @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > > > } > > > > > > > > > > > > for (i = outcnt; i < stream->outcnt; i++) { > > > > > > + if (SCTP_SO(stream, i)->ext) > > > > > > + kfree(SCTP_SO(stream, i)->ext->prio_head); > > > > > > + > > > > > > kfree(SCTP_SO(stream, i)->ext); > > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > > } > > > > > > -- > > > > > > 2.17.1 > > > > > > > > > > > This is not a proper fix: > > > > > 1. you shouldn't access "prio_head" outside stream_sched_prio.c. > > > > > 2. the prio_head you freed might be used by other out streams, freeing > > > > > it unconditionally would cause either a double free or use after free. > > > > > > > > > > I'm afraid we have to add a ".free_sid" in sctp_sched_ops, and > > > > > implement it for sctp_sched_prio, like: > > > > > > > > > > +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid) > > > > > +{ > > > > > + struct sctp_stream_priorities *prio = SCTP_SO(stream, > > > > > sid)->ext->prio_head; > > > > > + int i; > > > > > + > > > > > + if (!prio) > > > > > + return; > > > > > + > > > > > + SCTP_SO(stream, sid)->ext->prio_head = NULL; > > > > > + for (i = 0; i < stream->outcnt; i++) { > > > > > > > > Instead of checking all streams, the for() can/should be replaced by > > > > (from sctp_sched_prio_free): > > > > if (!list_empty(&prio->prio_sched)) > > > > return; > > > sctp_stream_outq_migrate() is called after unsched_all() for "stream", > > > list_empty(prio_sched) is expected to be true. > > > > Good point. Am I missing something or the 'prio_head == prio' below > > would always be false then as well? sorry, forgot to reply to this one :D after .unsched_all, multiple outstreams may have the same prio_head, which are not on any list (like stream->prio_list). so when freeing one outstream ext, it will need to go over all outstreams' exts and check if this outstream ext's prio is equal to that of any other outstreams. > > > > Anyhow, as this is moving to something that can potentially be called > > from other places afterwards, keeping the check doesn't hurt. > > > > > > > > Note that kfree(SCTP_SO(new, i)->ext) shouldn't have the reported > > > problem, as at that moment, the "new" stream hasn't been set > > > stream_sched yet. It means there's only one place that needs to > > > call free_sid in sctp_stream_outq_migrate(). > > > (Maybe Zhengchao can help us confirm this?) > > > > That's the case in Tetsuo's patch (earlier today) as well. Yet, if we > > have an official way to free a stream, if it's not error handling > > during initialization, it should use it. > right. > > > > > > > > > > > > > > > + if (SCTP_SO(stream, i)->ext && > > > > > + SCTP_SO(stream, i)->ext->prio_head == prio) > > > > > + return; > > > > > + } > > > > > + kfree(prio); > > > > > +} > > > > > + > > > > > static void sctp_sched_prio_free(struct sctp_stream *stream) > > > > > { > > > > > struct sctp_stream_priorities *prio, *n; > > > > > @@ -323,6 +340,7 @@ static struct sctp_sched_ops sctp_sched_prio = { > > > > > .get = sctp_sched_prio_get, > > > > > .init = sctp_sched_prio_init, > > > > > .init_sid = sctp_sched_prio_init_sid, > > > > > + .free_sid = sctp_sched_prio_free_sid, > > > > > .free = sctp_sched_prio_free, > > > > > .enqueue = sctp_sched_prio_enqueue, > > > > > .dequeue = sctp_sched_prio_dequeue, > > > > > > > > > > then call it in sctp_stream_outq_migrate(), like: > > > > > > > > > > +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid) > > > > > +{ > > > > > + struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream); > > > > > + > > > > > + sched->free_sid(stream, sid); > > > > > + kfree(SCTP_SO(stream, sid)->ext); > > > > > + SCTP_SO(stream, sid)->ext = NULL; > > > > > +} > > > > > + > > > > > /* Migrates chunks from stream queues to new stream queues if needed, > > > > > * but not across associations. Also, removes those chunks to streams > > > > > * higher than the new max. > > > > > @@ -70,16 +79,14 @@ static void sctp_stream_outq_migrate(struct > > > > > sctp_stream *stream, > > > > > * sctp_stream_update will swap ->out pointers. > > > > > */ > > > > > for (i = 0; i < outcnt; i++) { > > > > > - kfree(SCTP_SO(new, i)->ext); > > > > > + sctp_stream_free_ext(new, i); > > > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > } > > > > > } > > > > > > > > > > - for (i = outcnt; i < stream->outcnt; i++) { > > > > > - kfree(SCTP_SO(stream, i)->ext); > > > > > - SCTP_SO(stream, i)->ext = NULL; > > > > > - } > > > > > + for (i = outcnt; i < stream->outcnt; i++) > > > > > + sctp_stream_free_ext(new, i); > > > > > } > > > > > > > > > > Marcelo, do you see a better solution? > > > > > > > > No. Your suggestion is the best I could think of too. > > > > > > > > Another approach would be to expose sched->free and do all the freeing > > > > at once, like sctp_stream_free() does. But the above is looks cleaner > > > > and makes it evident that freeing 'ext' is not trivial. > > > > > > > > With the proposal above, sctp_sched_prio_free() becomes an > > > > optimization, if we can call it that. With the for/if replacement > > > > above, not even that, and should be removed. Including sctp_sched_ops > > > > 'free' pointer. > > > Or we extract the common code to another function, like > > > sctp_sched_prio_free_head(stream, prio), and pass prio as > > > NULL in sctp_sched_prio_free() for freeing all. > > > > > > > > > > > sctp_stream_free() then should be updated to use the new > > > > sctp_stream_free_ext() instead, instead of mangling it directly. > > > I thought about this, but there is ".free", which is more efficient > > > to free all prio than calling ".free_sid" outcnt times. > > > > How much more efficient, just by avoiding retpoline stuff on the > > indirect functional call or something else? > > in sctp_stream_free(): > .free() will be called one time to free all prios > while .free_sid will be called in a loop to free all prios: > for (i = 0; i < stream->outcnt; i++) > .free_sid(stream, i); > > inside either() .free or . free_sid() there is another loop: > for (i = 0; i < stream->outcnt; i++) > ... > > That's why I said using .free() in sctp_stream_free() will be more efficient. > > > > > > > > > I may move free_sid() out of sctp_stream_free_ext(), then in > > > sctp_stream_free() we can call sctp_stream_free_ext() without > > > calling free_sid(), or just remove sctp_stream_free_ext(). > > > > It's easier to maintain it if we have symmetric paths for initializing > > and for freeing it and less special cases. We already have > > sctp_stream_init_ext(), so having sctp_stream_free_ext() is not off. > didn't notice init_sid in sctp_stream_init_ext(), it makes sense to > have free_sid in sctp_stream_free_ext(). > > Thanks. > > > > > I'm happy to review any patch that also updates sctp_stream_free(), > > one way or another. > > > > > > > > Thanks. > > > > > > > > > > > Makes sense? > > > > > > > > Thanks, > > > > Marcelo
On Wed, Nov 23, 2022 at 01:48:01PM -0500, Xin Long wrote: > On Wed, Nov 23, 2022 at 1:30 PM Xin Long <lucien.xin@gmail.com> wrote: > > > > ( > > > > On Wed, Nov 23, 2022 at 1:10 PM Marcelo Ricardo Leitner > > <marcelo.leitner@gmail.com> wrote: > > > > > > On Wed, Nov 23, 2022 at 12:20:44PM -0500, Xin Long wrote: > > > > On Tue, Nov 22, 2022 at 6:35 PM Marcelo Ricardo Leitner > > > > <marcelo.leitner@gmail.com> wrote: > > > > > > > > > > On Fri, Nov 18, 2022 at 10:15:50PM -0500, Xin Long wrote: > > > > > > On Fri, Nov 18, 2022 at 3:48 AM Zhengchao Shao <shaozhengchao@huawei.com> wrote: > > > > > > > > > > > > > > When sctp_stream_outq_migrate() is called to release stream out resources, > > > > > > > the memory pointed to by prio_head in stream out is not released. > > > > > > > > > > > > > > The memory leak information is as follows: > > > > > > > unreferenced object 0xffff88801fe79f80 (size 64): > > > > > > > comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) > > > > > > > hex dump (first 32 bytes): > > > > > > > 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ > > > > > > > 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ > > > > > > > backtrace: > > > > > > > [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60 > > > > > > > [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770 > > > > > > > [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0 > > > > > > > [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30 > > > > > > > [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0 > > > > > > > [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0 > > > > > > > [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120 > > > > > > > [<ffffffff8755446a>] __sys_sendto+0x23a/0x340 > > > > > > > [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0 > > > > > > > [<ffffffff89978b49>] do_syscall_64+0x39/0xb0 > > > > > > > [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > > > > > > > > > > > Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") > > > > > > > Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com > > > > > > > Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> > > > > > > > --- > > > > > > > net/sctp/stream.c | 6 ++++++ > > > > > > > 1 file changed, 6 insertions(+) > > > > > > > > > > > > > > diff --git a/net/sctp/stream.c b/net/sctp/stream.c > > > > > > > index ef9fceadef8d..a17dc368876f 100644 > > > > > > > --- a/net/sctp/stream.c > > > > > > > +++ b/net/sctp/stream.c > > > > > > > @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > > > > * sctp_stream_update will swap ->out pointers. > > > > > > > */ > > > > > > > for (i = 0; i < outcnt; i++) { > > > > > > > + if (SCTP_SO(new, i)->ext) > > > > > > > + kfree(SCTP_SO(new, i)->ext->prio_head); > > > > > > > + > > > > > > > kfree(SCTP_SO(new, i)->ext); > > > > > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > > > @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > > > > } > > > > > > > > > > > > > > for (i = outcnt; i < stream->outcnt; i++) { > > > > > > > + if (SCTP_SO(stream, i)->ext) > > > > > > > + kfree(SCTP_SO(stream, i)->ext->prio_head); > > > > > > > + > > > > > > > kfree(SCTP_SO(stream, i)->ext); > > > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > > > } > > > > > > > -- > > > > > > > 2.17.1 > > > > > > > > > > > > > This is not a proper fix: > > > > > > 1. you shouldn't access "prio_head" outside stream_sched_prio.c. > > > > > > 2. the prio_head you freed might be used by other out streams, freeing > > > > > > it unconditionally would cause either a double free or use after free. > > > > > > > > > > > > I'm afraid we have to add a ".free_sid" in sctp_sched_ops, and > > > > > > implement it for sctp_sched_prio, like: > > > > > > > > > > > > +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid) > > > > > > +{ > > > > > > + struct sctp_stream_priorities *prio = SCTP_SO(stream, > > > > > > sid)->ext->prio_head; > > > > > > + int i; > > > > > > + > > > > > > + if (!prio) > > > > > > + return; > > > > > > + > > > > > > + SCTP_SO(stream, sid)->ext->prio_head = NULL; > > > > > > + for (i = 0; i < stream->outcnt; i++) { > > > > > > > > > > Instead of checking all streams, the for() can/should be replaced by > > > > > (from sctp_sched_prio_free): > > > > > if (!list_empty(&prio->prio_sched)) > > > > > return; > > > > sctp_stream_outq_migrate() is called after unsched_all() for "stream", > > > > list_empty(prio_sched) is expected to be true. > > > > > > Good point. Am I missing something or the 'prio_head == prio' below > > > would always be false then as well? > sorry, forgot to reply to this one :D :D > > after .unsched_all, multiple outstreams may have the same prio_head, > which are not on any list (like stream->prio_list). > > so when freeing one outstream ext, it will need to go over all outstreams' exts > and check if this outstream ext's prio is equal to that of any other outstreams. Understood. The check in sctp_sched_prio_free() is actually checking if the prio_head is not yet scheduled for freeing instead, right. Thanks. Hmm. This for() can be quite expensive then. :-( > > > > > > > Anyhow, as this is moving to something that can potentially be called > > > from other places afterwards, keeping the check doesn't hurt. > > > > > > > > > > > Note that kfree(SCTP_SO(new, i)->ext) shouldn't have the reported > > > > problem, as at that moment, the "new" stream hasn't been set > > > > stream_sched yet. It means there's only one place that needs to > > > > call free_sid in sctp_stream_outq_migrate(). > > > > (Maybe Zhengchao can help us confirm this?) > > > > > > That's the case in Tetsuo's patch (earlier today) as well. Yet, if we > > > have an official way to free a stream, if it's not error handling > > > during initialization, it should use it. > > right. > > > > > > > > > > > > > > > > > > > > + if (SCTP_SO(stream, i)->ext && > > > > > > + SCTP_SO(stream, i)->ext->prio_head == prio) > > > > > > + return; > > > > > > + } > > > > > > + kfree(prio); > > > > > > +} > > > > > > + > > > > > > static void sctp_sched_prio_free(struct sctp_stream *stream) > > > > > > { > > > > > > struct sctp_stream_priorities *prio, *n; > > > > > > @@ -323,6 +340,7 @@ static struct sctp_sched_ops sctp_sched_prio = { > > > > > > .get = sctp_sched_prio_get, > > > > > > .init = sctp_sched_prio_init, > > > > > > .init_sid = sctp_sched_prio_init_sid, > > > > > > + .free_sid = sctp_sched_prio_free_sid, > > > > > > .free = sctp_sched_prio_free, > > > > > > .enqueue = sctp_sched_prio_enqueue, > > > > > > .dequeue = sctp_sched_prio_dequeue, > > > > > > > > > > > > then call it in sctp_stream_outq_migrate(), like: > > > > > > > > > > > > +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid) > > > > > > +{ > > > > > > + struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream); > > > > > > + > > > > > > + sched->free_sid(stream, sid); > > > > > > + kfree(SCTP_SO(stream, sid)->ext); > > > > > > + SCTP_SO(stream, sid)->ext = NULL; > > > > > > +} > > > > > > + > > > > > > /* Migrates chunks from stream queues to new stream queues if needed, > > > > > > * but not across associations. Also, removes those chunks to streams > > > > > > * higher than the new max. > > > > > > @@ -70,16 +79,14 @@ static void sctp_stream_outq_migrate(struct > > > > > > sctp_stream *stream, > > > > > > * sctp_stream_update will swap ->out pointers. > > > > > > */ > > > > > > for (i = 0; i < outcnt; i++) { > > > > > > - kfree(SCTP_SO(new, i)->ext); > > > > > > + sctp_stream_free_ext(new, i); > > > > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > > } > > > > > > } > > > > > > > > > > > > - for (i = outcnt; i < stream->outcnt; i++) { > > > > > > - kfree(SCTP_SO(stream, i)->ext); > > > > > > - SCTP_SO(stream, i)->ext = NULL; > > > > > > - } > > > > > > + for (i = outcnt; i < stream->outcnt; i++) > > > > > > + sctp_stream_free_ext(new, i); > > > > > > } > > > > > > > > > > > > Marcelo, do you see a better solution? > > > > > > > > > > No. Your suggestion is the best I could think of too. > > > > > > > > > > Another approach would be to expose sched->free and do all the freeing > > > > > at once, like sctp_stream_free() does. But the above is looks cleaner > > > > > and makes it evident that freeing 'ext' is not trivial. > > > > > > > > > > With the proposal above, sctp_sched_prio_free() becomes an > > > > > optimization, if we can call it that. With the for/if replacement > > > > > above, not even that, and should be removed. Including sctp_sched_ops > > > > > 'free' pointer. > > > > Or we extract the common code to another function, like > > > > sctp_sched_prio_free_head(stream, prio), and pass prio as > > > > NULL in sctp_sched_prio_free() for freeing all. > > > > > > > > > > > > > > sctp_stream_free() then should be updated to use the new > > > > > sctp_stream_free_ext() instead, instead of mangling it directly. > > > > I thought about this, but there is ".free", which is more efficient > > > > to free all prio than calling ".free_sid" outcnt times. > > > > > > How much more efficient, just by avoiding retpoline stuff on the > > > indirect functional call or something else? > > > > in sctp_stream_free(): > > .free() will be called one time to free all prios > > while .free_sid will be called in a loop to free all prios: > > for (i = 0; i < stream->outcnt; i++) > > .free_sid(stream, i); > > > > inside either() .free or . free_sid() there is another loop: > > for (i = 0; i < stream->outcnt; i++) > > ... > > > > That's why I said using .free() in sctp_stream_free() will be more efficient. > > > > > > > > > > > > > I may move free_sid() out of sctp_stream_free_ext(), then in > > > > sctp_stream_free() we can call sctp_stream_free_ext() without > > > > calling free_sid(), or just remove sctp_stream_free_ext(). > > > > > > It's easier to maintain it if we have symmetric paths for initializing > > > and for freeing it and less special cases. We already have > > > sctp_stream_init_ext(), so having sctp_stream_free_ext() is not off. > > didn't notice init_sid in sctp_stream_init_ext(), it makes sense to > > have free_sid in sctp_stream_free_ext(). > > > > Thanks. > > > > > > > > I'm happy to review any patch that also updates sctp_stream_free(), > > > one way or another. > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > Makes sense? > > > > > > > > > > Thanks, > > > > > Marcelo
On Wed, Nov 23, 2022 at 2:01 PM Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> wrote: > > On Wed, Nov 23, 2022 at 01:48:01PM -0500, Xin Long wrote: > > On Wed, Nov 23, 2022 at 1:30 PM Xin Long <lucien.xin@gmail.com> wrote: > > > > > > ( > > > > > > On Wed, Nov 23, 2022 at 1:10 PM Marcelo Ricardo Leitner > > > <marcelo.leitner@gmail.com> wrote: > > > > > > > > On Wed, Nov 23, 2022 at 12:20:44PM -0500, Xin Long wrote: > > > > > On Tue, Nov 22, 2022 at 6:35 PM Marcelo Ricardo Leitner > > > > > <marcelo.leitner@gmail.com> wrote: > > > > > > > > > > > > On Fri, Nov 18, 2022 at 10:15:50PM -0500, Xin Long wrote: > > > > > > > On Fri, Nov 18, 2022 at 3:48 AM Zhengchao Shao <shaozhengchao@huawei.com> wrote: > > > > > > > > > > > > > > > > When sctp_stream_outq_migrate() is called to release stream out resources, > > > > > > > > the memory pointed to by prio_head in stream out is not released. > > > > > > > > > > > > > > > > The memory leak information is as follows: > > > > > > > > unreferenced object 0xffff88801fe79f80 (size 64): > > > > > > > > comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) > > > > > > > > hex dump (first 32 bytes): > > > > > > > > 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ > > > > > > > > 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ > > > > > > > > backtrace: > > > > > > > > [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60 > > > > > > > > [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770 > > > > > > > > [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0 > > > > > > > > [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30 > > > > > > > > [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0 > > > > > > > > [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0 > > > > > > > > [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120 > > > > > > > > [<ffffffff8755446a>] __sys_sendto+0x23a/0x340 > > > > > > > > [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0 > > > > > > > > [<ffffffff89978b49>] do_syscall_64+0x39/0xb0 > > > > > > > > [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > > > > > > > > > > > > > Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") > > > > > > > > Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com > > > > > > > > Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> > > > > > > > > --- > > > > > > > > net/sctp/stream.c | 6 ++++++ > > > > > > > > 1 file changed, 6 insertions(+) > > > > > > > > > > > > > > > > diff --git a/net/sctp/stream.c b/net/sctp/stream.c > > > > > > > > index ef9fceadef8d..a17dc368876f 100644 > > > > > > > > --- a/net/sctp/stream.c > > > > > > > > +++ b/net/sctp/stream.c > > > > > > > > @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > > > > > * sctp_stream_update will swap ->out pointers. > > > > > > > > */ > > > > > > > > for (i = 0; i < outcnt; i++) { > > > > > > > > + if (SCTP_SO(new, i)->ext) > > > > > > > > + kfree(SCTP_SO(new, i)->ext->prio_head); > > > > > > > > + > > > > > > > > kfree(SCTP_SO(new, i)->ext); > > > > > > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > > > > @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > > > > > } > > > > > > > > > > > > > > > > for (i = outcnt; i < stream->outcnt; i++) { > > > > > > > > + if (SCTP_SO(stream, i)->ext) > > > > > > > > + kfree(SCTP_SO(stream, i)->ext->prio_head); > > > > > > > > + > > > > > > > > kfree(SCTP_SO(stream, i)->ext); > > > > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > > > > } > > > > > > > > -- > > > > > > > > 2.17.1 > > > > > > > > > > > > > > > This is not a proper fix: > > > > > > > 1. you shouldn't access "prio_head" outside stream_sched_prio.c. > > > > > > > 2. the prio_head you freed might be used by other out streams, freeing > > > > > > > it unconditionally would cause either a double free or use after free. > > > > > > > > > > > > > > I'm afraid we have to add a ".free_sid" in sctp_sched_ops, and > > > > > > > implement it for sctp_sched_prio, like: > > > > > > > > > > > > > > +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid) > > > > > > > +{ > > > > > > > + struct sctp_stream_priorities *prio = SCTP_SO(stream, > > > > > > > sid)->ext->prio_head; > > > > > > > + int i; > > > > > > > + > > > > > > > + if (!prio) > > > > > > > + return; > > > > > > > + > > > > > > > + SCTP_SO(stream, sid)->ext->prio_head = NULL; > > > > > > > + for (i = 0; i < stream->outcnt; i++) { > > > > > > > > > > > > Instead of checking all streams, the for() can/should be replaced by > > > > > > (from sctp_sched_prio_free): > > > > > > if (!list_empty(&prio->prio_sched)) > > > > > > return; > > > > > sctp_stream_outq_migrate() is called after unsched_all() for "stream", > > > > > list_empty(prio_sched) is expected to be true. > > > > > > > > Good point. Am I missing something or the 'prio_head == prio' below > > > > would always be false then as well? > > sorry, forgot to reply to this one :D > > :D > > > > > after .unsched_all, multiple outstreams may have the same prio_head, > > which are not on any list (like stream->prio_list). > > > > so when freeing one outstream ext, it will need to go over all outstreams' exts > > and check if this outstream ext's prio is equal to that of any other outstreams. > > Understood. The check in sctp_sched_prio_free() is actually checking > if the prio_head is not yet scheduled for freeing instead, right. > Thanks. Hmm. This for() can be quite expensive then. :-( > > > > > > > > > > > Anyhow, as this is moving to something that can potentially be called > > > > from other places afterwards, keeping the check doesn't hurt. > > > > > > > > > > > > > > Note that kfree(SCTP_SO(new, i)->ext) shouldn't have the reported > > > > > problem, as at that moment, the "new" stream hasn't been set > > > > > stream_sched yet. It means there's only one place that needs to > > > > > call free_sid in sctp_stream_outq_migrate(). > > > > > (Maybe Zhengchao can help us confirm this?) > > > > > > > > That's the case in Tetsuo's patch (earlier today) as well. Yet, if we > > > > have an official way to free a stream, if it's not error handling > > > > during initialization, it should use it. > > > right. > > > > > > > > > > > > > > > > > > > > > > > > > + if (SCTP_SO(stream, i)->ext && > > > > > > > + SCTP_SO(stream, i)->ext->prio_head == prio) > > > > > > > + return; > > > > > > > + } > > > > > > > + kfree(prio); > > > > > > > +} > > > > > > > + > > > > > > > static void sctp_sched_prio_free(struct sctp_stream *stream) > > > > > > > { > > > > > > > struct sctp_stream_priorities *prio, *n; > > > > > > > @@ -323,6 +340,7 @@ static struct sctp_sched_ops sctp_sched_prio = { > > > > > > > .get = sctp_sched_prio_get, > > > > > > > .init = sctp_sched_prio_init, > > > > > > > .init_sid = sctp_sched_prio_init_sid, > > > > > > > + .free_sid = sctp_sched_prio_free_sid, > > > > > > > .free = sctp_sched_prio_free, > > > > > > > .enqueue = sctp_sched_prio_enqueue, > > > > > > > .dequeue = sctp_sched_prio_dequeue, > > > > > > > > > > > > > > then call it in sctp_stream_outq_migrate(), like: > > > > > > > > > > > > > > +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid) > > > > > > > +{ > > > > > > > + struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream); > > > > > > > + > > > > > > > + sched->free_sid(stream, sid); > > > > > > > + kfree(SCTP_SO(stream, sid)->ext); > > > > > > > + SCTP_SO(stream, sid)->ext = NULL; > > > > > > > +} > > > > > > > + > > > > > > > /* Migrates chunks from stream queues to new stream queues if needed, > > > > > > > * but not across associations. Also, removes those chunks to streams > > > > > > > * higher than the new max. > > > > > > > @@ -70,16 +79,14 @@ static void sctp_stream_outq_migrate(struct > > > > > > > sctp_stream *stream, > > > > > > > * sctp_stream_update will swap ->out pointers. > > > > > > > */ > > > > > > > for (i = 0; i < outcnt; i++) { > > > > > > > - kfree(SCTP_SO(new, i)->ext); > > > > > > > + sctp_stream_free_ext(new, i); > > > > > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > > > > > SCTP_SO(stream, i)->ext = NULL; > > > > > > > } > > > > > > > } > > > > > > > > > > > > > > - for (i = outcnt; i < stream->outcnt; i++) { > > > > > > > - kfree(SCTP_SO(stream, i)->ext); > > > > > > > - SCTP_SO(stream, i)->ext = NULL; > > > > > > > - } > > > > > > > + for (i = outcnt; i < stream->outcnt; i++) > > > > > > > + sctp_stream_free_ext(new, i); > > > > > > > } > > > > > > > > > > > > > > Marcelo, do you see a better solution? > > > > > > > > > > > > No. Your suggestion is the best I could think of too. > > > > > > > > > > > > Another approach would be to expose sched->free and do all the freeing > > > > > > at once, like sctp_stream_free() does. But the above is looks cleaner > > > > > > and makes it evident that freeing 'ext' is not trivial. > > > > > > > > > > > > With the proposal above, sctp_sched_prio_free() becomes an > > > > > > optimization, if we can call it that. With the for/if replacement > > > > > > above, not even that, and should be removed. Including sctp_sched_ops > > > > > > 'free' pointer. > > > > > Or we extract the common code to another function, like > > > > > sctp_sched_prio_free_head(stream, prio), and pass prio as > > > > > NULL in sctp_sched_prio_free() for freeing all. > > > > > > > > > > > > > > > > > sctp_stream_free() then should be updated to use the new > > > > > > sctp_stream_free_ext() instead, instead of mangling it directly. > > > > > I thought about this, but there is ".free", which is more efficient > > > > > to free all prio than calling ".free_sid" outcnt times. > > > > > > > > How much more efficient, just by avoiding retpoline stuff on the > > > > indirect functional call or something else? > > > > > > in sctp_stream_free(): > > > .free() will be called one time to free all prios > > > while .free_sid will be called in a loop to free all prios: > > > for (i = 0; i < stream->outcnt; i++) > > > .free_sid(stream, i); > > > > > > inside either() .free or . free_sid() there is another loop: > > > for (i = 0; i < stream->outcnt; i++) > > > ... > > > > > > That's why I said using .free() in sctp_stream_free() will be more efficient. > > > > > > > > > > > > > > > > > I may move free_sid() out of sctp_stream_free_ext(), then in > > > > > sctp_stream_free() we can call sctp_stream_free_ext() without > > > > > calling free_sid(), or just remove sctp_stream_free_ext(). > > > > > > > > It's easier to maintain it if we have symmetric paths for initializing > > > > and for freeing it and less special cases. We already have > > > > sctp_stream_init_ext(), so having sctp_stream_free_ext() is not off. > > > didn't notice init_sid in sctp_stream_init_ext(), it makes sense to > > > have free_sid in sctp_stream_free_ext(). > > > > > > Thanks. > > > > > > > > > > > I'm happy to review any patch that also updates sctp_stream_free(), > > > > one way or another. > > > > Hi, Zhengchao Would you please post v2 with the proposal above? (also add syzkaller-bugs@googlegroups.com into Cc list as Tetsuo suggested in another thread) Thanks.
On 2022/11/24 11:04, Xin Long wrote: > On Wed, Nov 23, 2022 at 2:01 PM Marcelo Ricardo Leitner > <marcelo.leitner@gmail.com> wrote: >> >> On Wed, Nov 23, 2022 at 01:48:01PM -0500, Xin Long wrote: >>> On Wed, Nov 23, 2022 at 1:30 PM Xin Long <lucien.xin@gmail.com> wrote: >>>> >>>> ( >>>> >>>> On Wed, Nov 23, 2022 at 1:10 PM Marcelo Ricardo Leitner >>>> <marcelo.leitner@gmail.com> wrote: >>>>> >>>>> On Wed, Nov 23, 2022 at 12:20:44PM -0500, Xin Long wrote: >>>>>> On Tue, Nov 22, 2022 at 6:35 PM Marcelo Ricardo Leitner >>>>>> <marcelo.leitner@gmail.com> wrote: >>>>>>> >>>>>>> On Fri, Nov 18, 2022 at 10:15:50PM -0500, Xin Long wrote: >>>>>>>> On Fri, Nov 18, 2022 at 3:48 AM Zhengchao Shao <shaozhengchao@huawei.com> wrote: >>>>>>>>> >>>>>>>>> When sctp_stream_outq_migrate() is called to release stream out resources, >>>>>>>>> the memory pointed to by prio_head in stream out is not released. >>>>>>>>> >>>>>>>>> The memory leak information is as follows: >>>>>>>>> unreferenced object 0xffff88801fe79f80 (size 64): >>>>>>>>> comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) >>>>>>>>> hex dump (first 32 bytes): >>>>>>>>> 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ >>>>>>>>> 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ >>>>>>>>> backtrace: >>>>>>>>> [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60 >>>>>>>>> [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770 >>>>>>>>> [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0 >>>>>>>>> [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30 >>>>>>>>> [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0 >>>>>>>>> [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0 >>>>>>>>> [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120 >>>>>>>>> [<ffffffff8755446a>] __sys_sendto+0x23a/0x340 >>>>>>>>> [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0 >>>>>>>>> [<ffffffff89978b49>] do_syscall_64+0x39/0xb0 >>>>>>>>> [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd >>>>>>>>> >>>>>>>>> Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") >>>>>>>>> Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com >>>>>>>>> Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> >>>>>>>>> --- >>>>>>>>> net/sctp/stream.c | 6 ++++++ >>>>>>>>> 1 file changed, 6 insertions(+) >>>>>>>>> >>>>>>>>> diff --git a/net/sctp/stream.c b/net/sctp/stream.c >>>>>>>>> index ef9fceadef8d..a17dc368876f 100644 >>>>>>>>> --- a/net/sctp/stream.c >>>>>>>>> +++ b/net/sctp/stream.c >>>>>>>>> @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, >>>>>>>>> * sctp_stream_update will swap ->out pointers. >>>>>>>>> */ >>>>>>>>> for (i = 0; i < outcnt; i++) { >>>>>>>>> + if (SCTP_SO(new, i)->ext) >>>>>>>>> + kfree(SCTP_SO(new, i)->ext->prio_head); >>>>>>>>> + >>>>>>>>> kfree(SCTP_SO(new, i)->ext); >>>>>>>>> SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; >>>>>>>>> SCTP_SO(stream, i)->ext = NULL; >>>>>>>>> @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, >>>>>>>>> } >>>>>>>>> >>>>>>>>> for (i = outcnt; i < stream->outcnt; i++) { >>>>>>>>> + if (SCTP_SO(stream, i)->ext) >>>>>>>>> + kfree(SCTP_SO(stream, i)->ext->prio_head); >>>>>>>>> + >>>>>>>>> kfree(SCTP_SO(stream, i)->ext); >>>>>>>>> SCTP_SO(stream, i)->ext = NULL; >>>>>>>>> } >>>>>>>>> -- >>>>>>>>> 2.17.1 >>>>>>>>> >>>>>>>> This is not a proper fix: >>>>>>>> 1. you shouldn't access "prio_head" outside stream_sched_prio.c. >>>>>>>> 2. the prio_head you freed might be used by other out streams, freeing >>>>>>>> it unconditionally would cause either a double free or use after free. >>>>>>>> >>>>>>>> I'm afraid we have to add a ".free_sid" in sctp_sched_ops, and >>>>>>>> implement it for sctp_sched_prio, like: >>>>>>>> >>>>>>>> +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid) >>>>>>>> +{ >>>>>>>> + struct sctp_stream_priorities *prio = SCTP_SO(stream, >>>>>>>> sid)->ext->prio_head; >>>>>>>> + int i; >>>>>>>> + >>>>>>>> + if (!prio) >>>>>>>> + return; >>>>>>>> + >>>>>>>> + SCTP_SO(stream, sid)->ext->prio_head = NULL; >>>>>>>> + for (i = 0; i < stream->outcnt; i++) { >>>>>>> >>>>>>> Instead of checking all streams, the for() can/should be replaced by >>>>>>> (from sctp_sched_prio_free): >>>>>>> if (!list_empty(&prio->prio_sched)) >>>>>>> return; >>>>>> sctp_stream_outq_migrate() is called after unsched_all() for "stream", >>>>>> list_empty(prio_sched) is expected to be true. >>>>> >>>>> Good point. Am I missing something or the 'prio_head == prio' below >>>>> would always be false then as well? >>> sorry, forgot to reply to this one :D >> >> :D >> >>> >>> after .unsched_all, multiple outstreams may have the same prio_head, >>> which are not on any list (like stream->prio_list). >>> >>> so when freeing one outstream ext, it will need to go over all outstreams' exts >>> and check if this outstream ext's prio is equal to that of any other outstreams. >> >> Understood. The check in sctp_sched_prio_free() is actually checking >> if the prio_head is not yet scheduled for freeing instead, right. >> Thanks. Hmm. This for() can be quite expensive then. :-( >> >>> >>>>> >>>>> Anyhow, as this is moving to something that can potentially be called >>>>> from other places afterwards, keeping the check doesn't hurt. >>>>> >>>>>> >>>>>> Note that kfree(SCTP_SO(new, i)->ext) shouldn't have the reported >>>>>> problem, as at that moment, the "new" stream hasn't been set >>>>>> stream_sched yet. It means there's only one place that needs to >>>>>> call free_sid in sctp_stream_outq_migrate(). >>>>>> (Maybe Zhengchao can help us confirm this?) >>>>> >>>>> That's the case in Tetsuo's patch (earlier today) as well. Yet, if we >>>>> have an official way to free a stream, if it's not error handling >>>>> during initialization, it should use it. >>>> right. >>>> >>>>> >>>>>> >>>>>>> >>>>>>>> + if (SCTP_SO(stream, i)->ext && >>>>>>>> + SCTP_SO(stream, i)->ext->prio_head == prio) >>>>>>>> + return; >>>>>>>> + } >>>>>>>> + kfree(prio); >>>>>>>> +} >>>>>>>> + >>>>>>>> static void sctp_sched_prio_free(struct sctp_stream *stream) >>>>>>>> { >>>>>>>> struct sctp_stream_priorities *prio, *n; >>>>>>>> @@ -323,6 +340,7 @@ static struct sctp_sched_ops sctp_sched_prio = { >>>>>>>> .get = sctp_sched_prio_get, >>>>>>>> .init = sctp_sched_prio_init, >>>>>>>> .init_sid = sctp_sched_prio_init_sid, >>>>>>>> + .free_sid = sctp_sched_prio_free_sid, >>>>>>>> .free = sctp_sched_prio_free, >>>>>>>> .enqueue = sctp_sched_prio_enqueue, >>>>>>>> .dequeue = sctp_sched_prio_dequeue, >>>>>>>> >>>>>>>> then call it in sctp_stream_outq_migrate(), like: >>>>>>>> >>>>>>>> +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid) >>>>>>>> +{ >>>>>>>> + struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream); >>>>>>>> + >>>>>>>> + sched->free_sid(stream, sid); >>>>>>>> + kfree(SCTP_SO(stream, sid)->ext); >>>>>>>> + SCTP_SO(stream, sid)->ext = NULL; >>>>>>>> +} >>>>>>>> + >>>>>>>> /* Migrates chunks from stream queues to new stream queues if needed, >>>>>>>> * but not across associations. Also, removes those chunks to streams >>>>>>>> * higher than the new max. >>>>>>>> @@ -70,16 +79,14 @@ static void sctp_stream_outq_migrate(struct >>>>>>>> sctp_stream *stream, >>>>>>>> * sctp_stream_update will swap ->out pointers. >>>>>>>> */ >>>>>>>> for (i = 0; i < outcnt; i++) { >>>>>>>> - kfree(SCTP_SO(new, i)->ext); >>>>>>>> + sctp_stream_free_ext(new, i); >>>>>>>> SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; >>>>>>>> SCTP_SO(stream, i)->ext = NULL; >>>>>>>> } >>>>>>>> } >>>>>>>> >>>>>>>> - for (i = outcnt; i < stream->outcnt; i++) { >>>>>>>> - kfree(SCTP_SO(stream, i)->ext); >>>>>>>> - SCTP_SO(stream, i)->ext = NULL; >>>>>>>> - } >>>>>>>> + for (i = outcnt; i < stream->outcnt; i++) >>>>>>>> + sctp_stream_free_ext(new, i); >>>>>>>> } >>>>>>>> >>>>>>>> Marcelo, do you see a better solution? >>>>>>> >>>>>>> No. Your suggestion is the best I could think of too. >>>>>>> >>>>>>> Another approach would be to expose sched->free and do all the freeing >>>>>>> at once, like sctp_stream_free() does. But the above is looks cleaner >>>>>>> and makes it evident that freeing 'ext' is not trivial. >>>>>>> >>>>>>> With the proposal above, sctp_sched_prio_free() becomes an >>>>>>> optimization, if we can call it that. With the for/if replacement >>>>>>> above, not even that, and should be removed. Including sctp_sched_ops >>>>>>> 'free' pointer. >>>>>> Or we extract the common code to another function, like >>>>>> sctp_sched_prio_free_head(stream, prio), and pass prio as >>>>>> NULL in sctp_sched_prio_free() for freeing all. >>>>>> >>>>>>> >>>>>>> sctp_stream_free() then should be updated to use the new >>>>>>> sctp_stream_free_ext() instead, instead of mangling it directly. >>>>>> I thought about this, but there is ".free", which is more efficient >>>>>> to free all prio than calling ".free_sid" outcnt times. >>>>> >>>>> How much more efficient, just by avoiding retpoline stuff on the >>>>> indirect functional call or something else? >>>> >>>> in sctp_stream_free(): >>>> .free() will be called one time to free all prios >>>> while .free_sid will be called in a loop to free all prios: >>>> for (i = 0; i < stream->outcnt; i++) >>>> .free_sid(stream, i); >>>> >>>> inside either() .free or . free_sid() there is another loop: >>>> for (i = 0; i < stream->outcnt; i++) >>>> ... >>>> >>>> That's why I said using .free() in sctp_stream_free() will be more efficient. >>>> >>>>> >>>>>> >>>>>> I may move free_sid() out of sctp_stream_free_ext(), then in >>>>>> sctp_stream_free() we can call sctp_stream_free_ext() without >>>>>> calling free_sid(), or just remove sctp_stream_free_ext(). >>>>> >>>>> It's easier to maintain it if we have symmetric paths for initializing >>>>> and for freeing it and less special cases. We already have >>>>> sctp_stream_init_ext(), so having sctp_stream_free_ext() is not off. >>>> didn't notice init_sid in sctp_stream_init_ext(), it makes sense to >>>> have free_sid in sctp_stream_free_ext(). >>>> >>>> Thanks. >>>> >>>>> >>>>> I'm happy to review any patch that also updates sctp_stream_free(), >>>>> one way or another. >>>>> > Hi, Zhengchao > > Would you please post v2 with the proposal above? > (also add syzkaller-bugs@googlegroups.com into Cc list as Tetsuo > suggested in another thread) > > Thanks. OK， I will send V2 as soon as I have tested patch. Zhengchao Shao
diff --git a/net/sctp/stream.c b/net/sctp/stream.c index ef9fceadef8d..a17dc368876f 100644 --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, * sctp_stream_update will swap ->out pointers. */ for (i = 0; i < outcnt; i++) { + if (SCTP_SO(new, i)->ext) + kfree(SCTP_SO(new, i)->ext->prio_head); + kfree(SCTP_SO(new, i)->ext); SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; SCTP_SO(stream, i)->ext = NULL; @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, } for (i = outcnt; i < stream->outcnt; i++) { + if (SCTP_SO(stream, i)->ext) + kfree(SCTP_SO(stream, i)->ext->prio_head); + kfree(SCTP_SO(stream, i)->ext); SCTP_SO(stream, i)->ext = NULL; }
When sctp_stream_outq_migrate() is called to release stream out resources, the memory pointed to by prio_head in stream out is not released. The memory leak information is as follows: unreferenced object 0xffff88801fe79f80 (size 64): comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) hex dump (first 32 bytes): 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ backtrace: [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60 [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770 [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0 [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30 [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0 [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0 [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120 [<ffffffff8755446a>] __sys_sendto+0x23a/0x340 [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0 [<ffffffff89978b49>] do_syscall_64+0x39/0xb0 [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> --- net/sctp/stream.c | 6 ++++++ 1 file changed, 6 insertions(+)