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af_unix: Annotate data-race of sk->sk_state in unix_stream_connect().

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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: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Kuniyuki Iwashima 2024-06-04 09:52:31 -07:00 committed by Paolo Abeni
parent eb0718fb3e
commit a9bf9c7dc6
1 changed files with 2 additions and 5 deletions
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7
net/unix/af_unix.c
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@ -1481,7 +1481,6 @@ 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)
@ -1571,9 +1570,7 @@ restart:
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;
@ -1588,7 +1585,7 @@ restart:
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);