6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kuniyuki Iwashima kuniyu@amazon.com
[ Upstream commit a9bf9c7dc6a5899c01cb8f6e773a66315a5cd4b7 ]
As small optimisation, unix_stream_connect() prefetches the client's sk->sk_state without unix_state_lock() and checks if it's TCP_CLOSE.
Later, sk->sk_state is checked again under unix_state_lock().
Let's use READ_ONCE() for the first check and TCP_CLOSE directly for the second check.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/unix/af_unix.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 4a43091c95419..53d67d540a574 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1491,7 +1491,6 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr, struct sk_buff *skb = NULL; long timeo; int err; - int st;
err = unix_validate_addr(sunaddr, addr_len); if (err) @@ -1577,9 +1576,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
Well, and we have to recheck the state after socket locked. */ - st = sk->sk_state; - - switch (st) { + switch (READ_ONCE(sk->sk_state)) { case TCP_CLOSE: /* This is ok... continue with connect */ break; @@ -1594,7 +1591,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
unix_state_lock_nested(sk, U_LOCK_SECOND);
- if (sk->sk_state != st) { + if (sk->sk_state != TCP_CLOSE) { unix_state_unlock(sk); unix_state_unlock(other); sock_put(other);