From: Jiayuan Chen <jiayuan.chen@linux.dev>
To: Sechang Lim <rhkrqnwk98@gmail.com>,
Eric Dumazet <edumazet@google.com>,
Neal Cardwell <ncardwell@google.com>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>
Cc: Kuniyuki Iwashima <kuniyu@google.com>,
Simon Horman <horms@kernel.org>, Lawrence Brakmo <brakmo@fb.com>,
Alexei Starovoitov <ast@kernel.org>,
Jiayuan Chen <jiayuan.chen@linux.dev>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
bpf@vger.kernel.org
Subject: Re: [PATCH net v3] tcp: clear sock_ops cb flags before force-closing a child socket
Date: Thu, 11 Jun 2026 19:47:32 +0800 [thread overview]
Message-ID: <ee8eb9dc-3692-44eb-b807-3699201ddc49@linux.dev> (raw)
In-Reply-To: <20260611092923.1895982-1-rhkrqnwk98@gmail.com>
On 6/11/26 5:29 PM, Sechang Lim wrote:
> A child socket inherits the listener's bpf_sock_ops_cb_flags via
> sk_clone_lock(). If its setup fails in tcp_v4_syn_recv_sock() /
> tcp_v6_syn_recv_sock(), the child is freed through put_and_exit, where
> inet_csk_prepare_forced_close() drops the socket lock and tcp_done() runs
> without it.
>
> If BPF_SOCK_OPS_STATE_CB_FLAG was inherited, tcp_done() -> tcp_set_state()
> calls tcp_call_bpf(), which expects the lock and trips sock_owned_by_me():
>
> WARNING: include/net/sock.h:1799 at tcp_set_state+0x433/0x550
> RIP: 0010:tcp_set_state+0x433/0x550 include/net/sock.h:1799
> Call Trace:
> <IRQ>
> tcp_done+0xba/0x250 net/ipv4/tcp.c:5095
> tcp_v4_syn_recv_sock+0x850/0xa50 net/ipv4/tcp_ipv4.c:1787
> tcp_check_req+0xf30/0x1360 net/ipv4/tcp_minisocks.c:926
> tcp_v4_rcv+0x1047/0x1b50 net/ipv4/tcp_ipv4.c:2164
> </IRQ>
>
> The child is freed before it is ever established, so it should run no
> sock_ops callback. Clear its cb flags in inet_csk_prepare_for_destroy_sock(),
> the common point for the IPv4, IPv6 and chtls forced-close paths and for the
> MPTCP ->syn_recv_sock() failure path (dispose_child), which reaches tcp_done()
> on a child that was never established too.
>
> Suggested-by: Jiayuan Chen <jiayuan.chen@linux.dev>
> Fixes: d44874910a26 ("bpf: Add BPF_SOCK_OPS_STATE_CB")
> Signed-off-by: Sechang Lim <rhkrqnwk98@gmail.com>
Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev>
prev parent reply other threads:[~2026-06-11 11:48 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-11 9:29 [PATCH net v3] tcp: clear sock_ops cb flags before force-closing a child socket Sechang Lim
2026-06-11 11:47 ` Jiayuan Chen [this message]
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