| Message ID | 20220202060158.6260-1-houtao1@huawei.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | b293dcc473d22a62dc6d78de2b15e4f49515db56 |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf-next,v2] bpf: use VM_MAP instead of VM_ALLOC for ringbuf | expand |
[ +Andrey ] On 2/2/22 7:01 AM, Hou Tao wrote: > After commit 2fd3fb0be1d1 ("kasan, vmalloc: unpoison VM_ALLOC pages > after mapping"), non-VM_ALLOC mappings will be marked as accessible > in __get_vm_area_node() when KASAN is enabled. But now the flag for > ringbuf area is VM_ALLOC, so KASAN will complain out-of-bound access > after vmap() returns. Because the ringbuf area is created by mapping > allocated pages, so use VM_MAP instead. > > After the change, info in /proc/vmallocinfo also changes from > [start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmalloc user > to > [start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmap user > > Reported-by: syzbot+5ad567a418794b9b5983@syzkaller.appspotmail.com > Signed-off-by: Hou Tao <houtao1@huawei.com> > --- > v2: > * explain why VM_ALLOC will lead to vmalloc-oob access Do you know which tree commit 2fd3fb0be1d1 is, looks like it's neither in bpf nor in bpf-next tree at the moment. Either way, I presume this fix should be routed via bpf tree rather than bpf-next? (I can add Fixes tag while applying.) > * add Reported-by tag > v1: https://lore.kernel.org/bpf/CANUnq3a+sT_qtO1wNQ3GnLGN7FLvSSgvit2UVgqQKRpUvs85VQ@mail.gmail.com/T/#t > --- > kernel/bpf/ringbuf.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c > index 638d7fd7b375..710ba9de12ce 100644 > --- a/kernel/bpf/ringbuf.c > +++ b/kernel/bpf/ringbuf.c > @@ -104,7 +104,7 @@ static struct bpf_ringbuf *bpf_ringbuf_area_alloc(size_t data_sz, int numa_node) > } > > rb = vmap(pages, nr_meta_pages + 2 * nr_data_pages, > - VM_ALLOC | VM_USERMAP, PAGE_KERNEL); > + VM_MAP | VM_USERMAP, PAGE_KERNEL); > if (rb) { > kmemleak_not_leak(pages); > rb->pages = pages; >
Hi, > On 2/2/22 7:01 AM, Hou Tao wrote: > > After commit 2fd3fb0be1d1 ("kasan, vmalloc: unpoison VM_ALLOC pages > > after mapping"), non-VM_ALLOC mappings will be marked as accessible > > in __get_vm_area_node() when KASAN is enabled. But now the flag for > > ringbuf area is VM_ALLOC, so KASAN will complain out-of-bound access > > after vmap() returns. Because the ringbuf area is created by mapping > > allocated pages, so use VM_MAP instead. > > > > After the change, info in /proc/vmallocinfo also changes from > > [start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmalloc user > > to > > [start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmap user > > > > Reported-by: syzbot+5ad567a418794b9b5983@syzkaller.appspotmail.com > > Signed-off-by: Hou Tao <houtao1@huawei.com> > > --- > > v2: > > * explain why VM_ALLOC will lead to vmalloc-oob access > > Do you know which tree commit 2fd3fb0be1d1 is, looks like it's neither > in bpf nor in bpf-next tree at the moment. > It is on linux-next tree: $ git name-rev 2fd3fb0be1d1 2fd3fb0be1d1 tags/next-20220201~2^2~96 > Either way, I presume this fix should be routed via bpf tree rather > than bpf-next? (I can add Fixes tag while applying.) > Make sense and thanks for that. Regards, Tao > > * add Reported-by tag > > v1: https://lore.kernel.org/bpf/CANUnq3a+sT_qtO1wNQ3GnLGN7FLvSSgvit2UVgqQKRpUvs85VQ@mail.gmail.com/T/#t > > --- > > kernel/bpf/ringbuf.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c > > index 638d7fd7b375..710ba9de12ce 100644 > > --- a/kernel/bpf/ringbuf.c > > +++ b/kernel/bpf/ringbuf.c > > @@ -104,7 +104,7 @@ static struct bpf_ringbuf *bpf_ringbuf_area_alloc(size_t data_sz, int numa_node) > > } > > > > rb = vmap(pages, nr_meta_pages + 2 * nr_data_pages, > > - VM_ALLOC | VM_USERMAP, PAGE_KERNEL); > > + VM_MAP | VM_USERMAP, PAGE_KERNEL); > > if (rb) { > > kmemleak_not_leak(pages); > > rb->pages = pages; > > > >
On Wed, Feb 2, 2022 at 9:14 PM Hou Tao <hotforest@gmail.com> wrote: > > Hi, > > > On 2/2/22 7:01 AM, Hou Tao wrote: > > > After commit 2fd3fb0be1d1 ("kasan, vmalloc: unpoison VM_ALLOC pages > > > after mapping"), non-VM_ALLOC mappings will be marked as accessible > > > in __get_vm_area_node() when KASAN is enabled. But now the flag for > > > ringbuf area is VM_ALLOC, so KASAN will complain out-of-bound access > > > after vmap() returns. Because the ringbuf area is created by mapping > > > allocated pages, so use VM_MAP instead. > > > > > > After the change, info in /proc/vmallocinfo also changes from > > > [start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmalloc user > > > to > > > [start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmap user > > > > > > Reported-by: syzbot+5ad567a418794b9b5983@syzkaller.appspotmail.com > > > Signed-off-by: Hou Tao <houtao1@huawei.com> > > > --- > > > v2: > > > * explain why VM_ALLOC will lead to vmalloc-oob access > > > > Do you know which tree commit 2fd3fb0be1d1 is, looks like it's neither > > in bpf nor in bpf-next tree at the moment. > > > It is on linux-next tree: > > $ git name-rev 2fd3fb0be1d1 > 2fd3fb0be1d1 tags/next-20220201~2^2~96 > > > Either way, I presume this fix should be routed via bpf tree rather > > than bpf-next? (I can add Fixes tag while applying.) > > > Make sense and thanks for that. Added Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it") and pushed to bpf tree, thanks. > > Regards, > Tao > > > > * add Reported-by tag > > > v1: https://lore.kernel.org/bpf/CANUnq3a+sT_qtO1wNQ3GnLGN7FLvSSgvit2UVgqQKRpUvs85VQ@mail.gmail.com/T/#t > > > --- > > > kernel/bpf/ringbuf.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c > > > index 638d7fd7b375..710ba9de12ce 100644 > > > --- a/kernel/bpf/ringbuf.c > > > +++ b/kernel/bpf/ringbuf.c > > > @@ -104,7 +104,7 @@ static struct bpf_ringbuf *bpf_ringbuf_area_alloc(size_t data_sz, int numa_node) > > > } > > > > > > rb = vmap(pages, nr_meta_pages + 2 * nr_data_pages, > > > - VM_ALLOC | VM_USERMAP, PAGE_KERNEL); > > > + VM_MAP | VM_USERMAP, PAGE_KERNEL); > > > if (rb) { > > > kmemleak_not_leak(pages); > > > rb->pages = pages; > > > > > > >
Hello: This patch was applied to bpf/bpf.git (master) by Andrii Nakryiko <andrii@kernel.org>: On Wed, 2 Feb 2022 14:01:58 +0800 you wrote: > After commit 2fd3fb0be1d1 ("kasan, vmalloc: unpoison VM_ALLOC pages > after mapping"), non-VM_ALLOC mappings will be marked as accessible > in __get_vm_area_node() when KASAN is enabled. But now the flag for > ringbuf area is VM_ALLOC, so KASAN will complain out-of-bound access > after vmap() returns. Because the ringbuf area is created by mapping > allocated pages, so use VM_MAP instead. > > [...] Here is the summary with links: - [bpf-next,v2] bpf: use VM_MAP instead of VM_ALLOC for ringbuf https://git.kernel.org/bpf/bpf/c/b293dcc473d2 You are awesome, thank you!
diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c index 638d7fd7b375..710ba9de12ce 100644 --- a/kernel/bpf/ringbuf.c +++ b/kernel/bpf/ringbuf.c @@ -104,7 +104,7 @@ static struct bpf_ringbuf *bpf_ringbuf_area_alloc(size_t data_sz, int numa_node) } rb = vmap(pages, nr_meta_pages + 2 * nr_data_pages, - VM_ALLOC | VM_USERMAP, PAGE_KERNEL); + VM_MAP | VM_USERMAP, PAGE_KERNEL); if (rb) { kmemleak_not_leak(pages); rb->pages = pages;
After commit 2fd3fb0be1d1 ("kasan, vmalloc: unpoison VM_ALLOC pages after mapping"), non-VM_ALLOC mappings will be marked as accessible in __get_vm_area_node() when KASAN is enabled. But now the flag for ringbuf area is VM_ALLOC, so KASAN will complain out-of-bound access after vmap() returns. Because the ringbuf area is created by mapping allocated pages, so use VM_MAP instead. After the change, info in /proc/vmallocinfo also changes from [start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmalloc user to [start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmap user Reported-by: syzbot+5ad567a418794b9b5983@syzkaller.appspotmail.com Signed-off-by: Hou Tao <houtao1@huawei.com> --- v2: * explain why VM_ALLOC will lead to vmalloc-oob access * add Reported-by tag v1: https://lore.kernel.org/bpf/CANUnq3a+sT_qtO1wNQ3GnLGN7FLvSSgvit2UVgqQKRpUvs85VQ@mail.gmail.com/T/#t --- kernel/bpf/ringbuf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)