netdev - Re: [PATCH v8 bpf-next/net 1/6] tcp: Save lock_sock() for memcg in inet_csk

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Message-ID: <CAAVpQUBZT4dX9hU8h6s8ew5BYX9C6yBPaRODP4zM3F-=BB4Dtw@mail.gmail.com>
Date: Wed, 17 Sep 2025 00:03:28 -0700
From: Kuniyuki Iwashima <kuniyu@...gle.com>
To: kernel test robot <oliver.sang@...el.com>
Cc: oe-lkp@...ts.linux.dev, lkp@...el.com, 
	Shakeel Butt <shakeel.butt@...ux.dev>, netdev@...r.kernel.org, ltp@...ts.linux.it, 
	Alexei Starovoitov <ast@...nel.org>, Andrii Nakryiko <andrii@...nel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, Martin KaFai Lau <martin.lau@...ux.dev>, 
	John Fastabend <john.fastabend@...il.com>, Stanislav Fomichev <sdf@...ichev.me>, 
	Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>, 
	Roman Gushchin <roman.gushchin@...ux.dev>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Neal Cardwell <ncardwell@...gle.com>, Willem de Bruijn <willemb@...gle.com>, 
	Mina Almasry <almasrymina@...gle.com>, Kuniyuki Iwashima <kuni1840@...il.com>, bpf@...r.kernel.org
Subject: Re: [PATCH v8 bpf-next/net 1/6] tcp: Save lock_sock() for memcg in inet_csk_accept().

On Tue, Sep 16, 2025 at 11:37 PM kernel test robot
<oliver.sang@...el.com> wrote:
>
>
> Hello,
>
> kernel test robot noticed "BUG:KASAN:slab-out-of-bounds_in__inet_accept" on:
>
> commit: d465aa09942825d93a377c3715c464e8f6827f13 ("[PATCH v8 bpf-next/net 1/6] tcp: Save lock_sock() for memcg in inet_csk_accept().")
> url: https://github.com/intel-lab-lkp/linux/commits/Kuniyuki-Iwashima/tcp-Save-lock_sock-for-memcg-in-inet_csk_accept/20250911-032312
> base: https://git.kernel.org/cgit/linux/kernel/git/bpf/bpf-next.git net
> patch link: https://lore.kernel.org/all/20250910192057.1045711-2-kuniyu@google.com/
> patch subject: [PATCH v8 bpf-next/net 1/6] tcp: Save lock_sock() for memcg in inet_csk_accept().
>
> in testcase: ltp
> version: ltp-x86_64-c6660a3e0-1_20250913
> with following parameters:
>
>         test: net.features
>
>
>
> config: x86_64-rhel-9.4-ltp
> compiler: gcc-14
> test machine: 8 threads 1 sockets Intel(R) Core(TM) i7-4790T CPU @ 2.70GHz (Haswell) with 16G memory
>
> (please refer to attached dmesg/kmsg for entire log/backtrace)
>
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@...el.com>
> | Closes: https://lore.kernel.org/oe-lkp/202509171359.658ddb38-lkp@intel.com
>
>
> The kernel config and materials to reproduce are available at:
> https://download.01.org/0day-ci/archive/20250917/202509171359.658ddb38-lkp@intel.com
>
>
> we saw a lot of "BUG:KASAN:slab-out-of-bounds_in__inet_accept" issue in dmesg
> uploaded to above link, below is just one example:
>
>
> [  468.984291][T30180] ==================================================================
> [  468.992753][T30180] BUG: KASAN: slab-out-of-bounds in __inet_accept+0x5c6/0x640

Oh I misused sk_is_mptcp() which assumes that sk_is_tcp()
is always true and should not be used if sk_is_tcp() is false for
SCTP, so sk_is_mptcp() test was unnecessary

I'll remove it, thanks!