6.1-stable review patch. If anyone has any objections, please let me know.
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From: Kuniyuki Iwashima kuniyu@google.com
[ Upstream commit 2a5a4841846b079b5fca5752fe94e59346fbda40 ]
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 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 --- 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 01de31a0f22fe..2c33d787b860d 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -577,6 +577,11 @@ 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); @@ -611,10 +616,16 @@ 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); @@ -2593,11 +2604,6 @@ 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 *);