Re: WARNING in xfrm_state_fini

[Cong Wang]

On Tue, Nov 21, 2017 at 2:00 AM, syzbot
<bot+427f0a9138719ba183c0d37d8c2d070567f7761a@xxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:
> Hello,
>
> syzkaller hit the following crash on
> c8a0739b185d11d6e2ca7ad9f5835841d1cfc765
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> C reproducer is attached
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers
>
>
> Kernel panic - not syncing: panic_on_warn set ...
>
> CPU: 0 PID: 21 Comm: kworker/u4:1 Not tainted 4.14.0+ #187
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Workqueue: netns cleanup_net
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x194/0x257 lib/dump_stack.c:53
>  panic+0x1e4/0x41c kernel/panic.c:183
>  __warn+0x1dc/0x200 kernel/panic.c:547
>  report_bug+0x211/0x2d0 lib/bug.c:184
>  fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:177
>  fixup_bug arch/x86/kernel/traps.c:246 [inline]
>  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:295
>  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
>  invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:926
> RIP: 0010:xfrm_state_fini+0x46a/0x620 net/xfrm/xfrm_state.c:2323
> RSP: 0018:ffff8801d9ce70f0 EFLAGS: 00010293
> RAX: ffff8801d9cde580 RBX: ffff8801ccf50040 RCX: ffffffff845cb0fa
> RDX: 0000000000000000 RSI: 1ffff1003b39bdd1 RDI: ffffed003b39ce10
> RBP: ffff8801d9ce7248 R08: 1ffff1003b39cda4 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003b39ce20
> R13: ffff8801d9ce7220 R14: 1ffff1003b39ce24 R15: ffff8801ccf51500
>  xfrm_net_exit+0x25/0x30 net/xfrm/xfrm_policy.c:2957

User-space uses proto==0 as a wildcard, but xfrm_id_proto_match()
doesn't consider it as a match with IPSEC_PROTO_ANY, in this case
it should match all. Not sure if the following patch is the best way to
fix it, or perhaps x->id.proto should be initialized to some of these 3
values, but looking into ->init_temprop() it is not the case.


diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index dc28a98ce97c..8752f8b2c57f 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1370,7 +1370,8 @@ static inline int xfrm_state_kern(const struct
xfrm_state *x)
 static inline int xfrm_id_proto_match(u8 proto, u8 userproto)
 {
        return (!userproto || proto == userproto ||
-               (userproto == IPSEC_PROTO_ANY && (proto == IPPROTO_AH ||
+               (userproto == IPSEC_PROTO_ANY && (!proto ||
+                                                 proto == IPPROTO_AH ||
                                                  proto == IPPROTO_ESP ||
                                                  proto == IPPROTO_COMP)));
 }