| Message ID | 20210816073832.199701-1-mudongliangabcd@gmail.com (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: xfrm: fix bug in ipcomp_free_scratches | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Guessed tree name to be net-next |
| netdev/subject_prefix | warning | Target tree name not specified in the subject |
| netdev/cc_maintainers | success | CCed 5 of 5 maintainers |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | warning | WARNING: Missing a blank line after declarations |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
On Mon, Aug 16, 2021 at 03:38:29PM +0800, Dongliang Mu wrote: > > - for_each_possible_cpu(i) > - vfree(*per_cpu_ptr(scratches, i)); > + for_each_possible_cpu(i) { > + void *scratch = *per_cpu_ptr(scratches, i); > + if (!scratch) > + vfree(scratch); > + } This patch is unnecessary. Please check the implementation of vfree, it already checks for NULL pointers just like most of our free primitives. Cheers,
On Mon, Aug 16, 2021 at 3:53 PM Herbert Xu <herbert@gondor.apana.org.au> wrote: > > On Mon, Aug 16, 2021 at 03:38:29PM +0800, Dongliang Mu wrote: > > > > - for_each_possible_cpu(i) > > - vfree(*per_cpu_ptr(scratches, i)); > > + for_each_possible_cpu(i) { > > + void *scratch = *per_cpu_ptr(scratches, i); > > + if (!scratch) > > + vfree(scratch); > > + } > > This patch is unnecessary. Please check the implementation of > vfree, it already checks for NULL pointers just like most of our > free primitives. Yes, you're right. Let me double-check the code and find out where the problem is. > > Cheers, > -- > Email: Herbert Xu <herbert@gondor.apana.org.au> > Home Page: http://gondor.apana.org.au/~herbert/ > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
On Mon, Aug 16, 2021 at 3:53 PM Herbert Xu <herbert@gondor.apana.org.au> wrote: > > On Mon, Aug 16, 2021 at 03:38:29PM +0800, Dongliang Mu wrote: > > > > - for_each_possible_cpu(i) > > - vfree(*per_cpu_ptr(scratches, i)); > > + for_each_possible_cpu(i) { > > + void *scratch = *per_cpu_ptr(scratches, i); > > + if (!scratch) > > + vfree(scratch); > > + } > > This patch is unnecessary. Please check the implementation of > vfree, it already checks for NULL pointers just like most of our > free primitives. Hi Herbert, since there is no reproducer in the syzbot, I guess the problem might be: if vmalloc_node in the ipcomp_alloc_scratches returns a NULL pointer, it directly returns NULL without updating the per_cpu_ptr(scratches, i). Therefore, in the ipcomp_free_scratches, vfree will take an invalid and outdated per_cpu_ptr as its argument, leading to the bug - BUG: unable to handle kernel paging request in ipcomp_free_scratches. Any idea? > > Cheers, > -- > Email: Herbert Xu <herbert@gondor.apana.org.au> > Home Page: http://gondor.apana.org.au/~herbert/ > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c index cb40ff0ff28d..9588ac05ab27 100644 --- a/net/xfrm/xfrm_ipcomp.c +++ b/net/xfrm/xfrm_ipcomp.c @@ -199,8 +199,11 @@ static void ipcomp_free_scratches(void) if (!scratches) return; - for_each_possible_cpu(i) - vfree(*per_cpu_ptr(scratches, i)); + for_each_possible_cpu(i) { + void *scratch = *per_cpu_ptr(scratches, i); + if (!scratch) + vfree(scratch); + } free_percpu(scratches); }
In ipcomp_alloc_scratches, if the vmalloc fails, there leaves a NULL pointer. However, ipcomp_free_scratches does not check the per_pcu_ptr pointer when invoking vfree. Fix this by adding a sanity check before vfree. Call Trace: ipcomp_free_scratches+0xbc/0x160 net/xfrm/xfrm_ipcomp.c:203 ipcomp_free_data net/xfrm/xfrm_ipcomp.c:312 [inline] ipcomp_init_state+0x77c/0xa40 net/xfrm/xfrm_ipcomp.c:364 ipcomp6_init_state+0xc2/0x700 net/ipv6/ipcomp6.c:154 __xfrm_init_state+0x995/0x15c0 net/xfrm/xfrm_state.c:2648 xfrm_init_state+0x1a/0x70 net/xfrm/xfrm_state.c:2675 pfkey_msg2xfrm_state net/key/af_key.c:1287 [inline] pfkey_add+0x1a64/0x2cd0 net/key/af_key.c:1504 pfkey_process+0x685/0x7e0 net/key/af_key.c:2837 pfkey_sendmsg+0x43a/0x820 net/key/af_key.c:3676 sock_sendmsg_nosec net/socket.c:703 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:723 Reported-by: syzbot+b9cfd1cc5d57ee0a09ab@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Fixes: 6fccab671f2f ("ipsec: ipcomp - Merge IPComp impl") Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com> --- net/xfrm/xfrm_ipcomp.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)