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v6.15.11
linux-stable/net/unix
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Kuniyuki Iwashima ee53244b17 af_unix: Don't set -ECONNRESET for consumed OOB skb. 
[ Upstream commit 2a5a484184 ]

Christian Brauner reported that even after MSG_OOB data is consumed,
calling close() on the receiver socket causes the peer's recv() to
return -ECONNRESET:

  1. send() and recv() an OOB data.

    >>> from socket import *
    >>> s1, s2 = socketpair(AF_UNIX, SOCK_STREAM)
    >>> s1.send(b'x', MSG_OOB)
    1
    >>> s2.recv(1, MSG_OOB)
    b'x'

  2. close() for s2 sets ECONNRESET to s1->sk_err even though
     s2 consumed the OOB data

    >>> s2.close()
    >>> s1.recv(10, MSG_DONTWAIT)
    ...
    ConnectionResetError: [Errno 104] Connection reset by peer

Even after being consumed, the skb holding the OOB 1-byte data stays in
the recv queue to mark the OOB boundary and break recv() at that point.

This must be considered while close()ing a socket.

Let's skip the leading consumed OOB skb while checking the -ECONNRESET
condition in unix_release_sock().

Fixes: 314001f0bf ("af_unix: Add OOB support")
Reported-by: Christian Brauner <brauner@kernel.org>
Closes: https://lore.kernel.org/netdev/20250529-sinkt-abfeuern-e7b08200c6b0@brauner/
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Link: https://patch.msgid.link/20250619041457.1132791-4-kuni1840@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-07-06 11:04:15 +02:00
..
af_unix.c af_unix: Don't set -ECONNRESET for consumed OOB skb. 2025-07-06 11:04:15 +02:00
af_unix.h unix: fix up for "apparmor: add fine grained af_unix mediation" 2025-03-26 09:31:18 -07:00
diag.c af_unix: Clean up #include under net/unix/. 2025-03-25 04:30:07 -07:00
garbage.c af_unix: Clean up #include under net/unix/. 2025-03-25 04:30:07 -07:00
Kconfig af_unix: Add a prompt to CONFIG_AF_UNIX_OOB 2024-12-19 19:16:15 -08:00
Makefile
sysctl_net_unix.c af_unix: Clean up #include under net/unix/. 2025-03-25 04:30:07 -07:00
unix_bpf.c af_unix: Explicitly include headers for non-pointer struct fields. 2025-03-25 04:30:07 -07:00