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([2601:647:6700:3390::c8d1]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2365de781b1sm109928585ad.89.2025.06.18.21.15.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Jun 2025 21:15:04 -0700 (PDT) From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Rao Shoaib , Kuniyuki Iwashima , Kuniyuki Iwashima , netdev@vger.kernel.org, Christian Brauner Subject: [PATCH v2 net 3/4] af_unix: Don't set -ECONNRESET for consumed OOB skb. Date: Wed, 18 Jun 2025 21:13:57 -0700 Message-ID: <20250619041457.1132791-4-kuni1840@gmail.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250619041457.1132791-1-kuni1840@gmail.com> References: <20250619041457.1132791-1-kuni1840@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Kuniyuki Iwashima 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: 314001f0bf92 ("af_unix: Add OOB support") Reported-by: Christian Brauner Closes: https://lore.kernel.org/netdev/20250529-sinkt-abfeuern-e7b08200c6b0@brauner/ Signed-off-by: Kuniyuki Iwashima --- v2: Reuse the existing path for non-listener and skip the leading consumed OOB skb instead of freeing it v1: https://lore.kernel.org/netdev/20250618043453.281247-1-kuni1840@gmail.com/ --- net/unix/af_unix.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 5392aa53cbc8..52b155123985 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -660,6 +660,11 @@ static void unix_sock_destructor(struct sock *sk) #endif } +static unsigned int unix_skb_len(const struct sk_buff *skb) +{ + return skb->len - UNIXCB(skb).consumed; +} + static void unix_release_sock(struct sock *sk, int embrion) { struct unix_sock *u = unix_sk(sk); @@ -694,10 +699,16 @@ static void unix_release_sock(struct sock *sk, int embrion) if (skpair != NULL) { if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) { + struct sk_buff *skb = skb_peek(&sk->sk_receive_queue); + +#if IS_ENABLED(CONFIG_AF_UNIX_OOB) + if (skb && !unix_skb_len(skb)) + skb = skb_peek_next(skb, &sk->sk_receive_queue); +#endif unix_state_lock(skpair); /* No more writes */ WRITE_ONCE(skpair->sk_shutdown, SHUTDOWN_MASK); - if (!skb_queue_empty_lockless(&sk->sk_receive_queue) || embrion) + if (skb || embrion) WRITE_ONCE(skpair->sk_err, ECONNRESET); unix_state_unlock(skpair); skpair->sk_state_change(skpair); @@ -2661,11 +2672,6 @@ static long unix_stream_data_wait(struct sock *sk, long timeo, return timeo; } -static unsigned int unix_skb_len(const struct sk_buff *skb) -{ - return skb->len - UNIXCB(skb).consumed; -} - struct unix_stream_read_state { int (*recv_actor)(struct sk_buff *, int, int, struct unix_stream_read_state *); -- 2.49.0