This is a note to let you know that I've just added the patch titled
af_unix: Annotate data-race of sk->sk_state in unix_stream_connect().
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
af_unix-annotate-data-race-of-sk-sk_state-in-unix_st.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit aeec58466a73081c275584e95c683b252b99a215
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Tue Jun 4 09:52:31 2024 -0700
af_unix: Annotate data-race of sk->sk_state in unix_stream_connect().
[ 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@xxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 9800d255a8bc7..628b3fcc74227 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1371,7 +1371,6 @@ 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)
@@ -1455,9 +1454,7 @@ 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;
@@ -1472,7 +1469,7 @@ 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);
