Re: [PATCH net v3] net/tcp: Disable TCP-AO static key after RCU grace period

[Kuniyuki Iwashima <kuniyu@amazon.com>]

From: Dmitry Safonov <0x7f454c46@gmail.com>
Date: Fri, 2 Aug 2024 03:00:59 +0100
> On Fri, 2 Aug 2024 at 02:03, Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
> >
> > From: Dmitry Safonov <0x7f454c46@gmail.com>
> > Date: Fri, 2 Aug 2024 01:37:28 +0100
> > > On Thu, 1 Aug 2024 at 01:13, Dmitry Safonov via B4 Relay
> > > <devnull+0x7f454c46.gmail.com@kernel.org> wrote:
> > > >
> > > > From: Dmitry Safonov <0x7f454c46@gmail.com>
> > > [..]
> > > > Happened on netdev test-bot[1], so not a theoretical issue:
> > >
> > > Self-correction: I see a static_key fix in git.tip tree from a recent
> > > regression, which could lead to the same kind of failure. So, I'm not
> > > entirely sure the issue isn't theoretical.
> > > https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=224fa3552029
> >
> > My syzkaller instances recently started to report similar splats over
> > different places (TCP-AO/MD5, fl6, netfilter, perf, etc), and I was
> > suspecting a bug in the jump label side.
> 
> I'm glad I dropped you a hint :-)
> 
> > report19:2:jump_label: Fatal kernel bug, unexpected op at fl6_sock_lookup include/net/ipv6.h:414 [inline] [000000001bd3e3db] (e9 ee 00 00 00 != 0f 1f 44 00 00)) size:5 type:1
> > report23:1:jump_label: Fatal kernel bug, unexpected op at nf_skip_egress include/linux/netfilter_netdev.h:136 [inline] [00000000c1241913] (e9 e9 0a 00 00 != 0f 1f 44 00 00)) size:5 type:1
> > report45:2:jump_label: Fatal kernel bug, unexpected op at tcp_ao_required include/net/tcp.h:2776 [inline] [000000009a4b37e9] (eb 5a e8 e1 57 != 66 90 0f 1f 00)) size:2 type:1
> > report49:3:jump_label: Fatal kernel bug, unexpected op at perf_sw_event include/linux/perf_event.h:1432 [inline] [00000000c1f7a26c] (eb 24 e9 63 fe != 66 90 0f 1f 00)) size:2 type:1
> > report58:2:jump_label: Fatal kernel bug, unexpected op at tcp_md5_do_lookup include/net/tcp.h:1852 [inline] [00000000fbd24b58] (e9 8d 01 00 00 != 0f 1f 44 00 00)) size:5 type:1
> >
> > I'll cherry-pick the patch and see if it fixes them altogether.
> > It will take few days.

I haven't seen the splat so far after applying 224fa3552029.
Before that, syzkaller reported jump_label splats 4~5 times
everyday, so I think 224fa3552029 fixed the regression.

Thanks!