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Message-ID: <28a1a98c757e4a15b7eecdeae563a17fa5cb45cf.camel@redhat.com>
Subject: Re: [PATCH net 03/13] mptcp: fix lockless access in subflow ULP diag
From: Paolo Abeni <pabeni@redhat.com>
To: Eric Dumazet <edumazet@google.com>
Cc: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>, mptcp@lists.linux.dev, 
 Mat Martineau <martineau@kernel.org>, Geliang Tang <geliang@kernel.org>,
 "David S. Miller" <davem@davemloft.net>,  Jakub Kicinski <kuba@kernel.org>,
 Davide Caratti <dcaratti@redhat.com>, Shuah Khan <shuah@kernel.org>,
 netdev@vger.kernel.org, linux-kernel@vger.kernel.org, 
 linux-kselftest@vger.kernel.org, stable@vger.kernel.org, Boris Pismenny
 <borisp@nvidia.com>, John Fastabend <john.fastabend@gmail.com>
Date: Tue, 20 Feb 2024 18:33:20 +0100
In-Reply-To: <CANn89iK72hE16sQcGPUFG6Am_V-77PNJOYHgeAA6M+SD5UO13A@mail.gmail.com>
References: 
	<20240215-upstream-net-20240215-misc-fixes-v1-0-8c01a55d8f6a@kernel.org>
	 <20240215-upstream-net-20240215-misc-fixes-v1-3-8c01a55d8f6a@kernel.org>
	 <CANn89iJ=Oecw6OZDwmSYc9HJKQ_G32uN11L+oUcMu+TOD5Xiaw@mail.gmail.com>
	 <CANn89iJDypRXX-8S-UdqWgw73eOgt0+D74qUCLDkb0cRpFFXkg@mail.gmail.com>
	 <278c26d6f4042dc6dadb9742afe11b7fa610f0b2.camel@redhat.com>
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On Mon, 2024-02-19 at 19:33 +0100, Eric Dumazet wrote:
> On Mon, Feb 19, 2024 at 7:04=E2=80=AFPM Paolo Abeni <pabeni@redhat.com> w=
rote:
> > Thanks for the head-up. This later option looks preferable, to avoid
> > quit a bit of noise with _ONCE annotation. Is there a syzkaller splat I
> > could look at? if it landed on the ML, I missed it.
> >=20
>=20
> Not landed yet, here is the splat :
>=20
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
> WARNING: possible circular locking dependency detected
> 6.8.0-rc4-syzkaller-00212-g40b9385dd8e6 #0 Not tainted
> ------------------------------------------------------
> syz-executor.2/24141 is trying to acquire lock:
> ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at:
> tcp_diag_put_ulp net/ipv4/tcp_diag.c:100 [inline]
> ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at:
> tcp_diag_get_aux+0x738/0x830 net/ipv4/tcp_diag.c:137
>=20
> but task is already holding lock:
> ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock
> include/linux/spinlock.h:351 [inline]
> ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at:
> inet_diag_dump_icsk+0x39f/0x1f80 net/ipv4/inet_diag.c:1038

[Sorry for the latency]. Yes it looks like that checking the listener
status will work. I can test and send the formal patch - with the due
credits! - or do you prefer otherwise?

Thanks!

Paolo