netdev - [PATCH v1 net 4/4] af_unix: Fix data race around sk->sk

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Date: Fri, 1 Sep 2023 17:27:08 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>
CC: Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
	<kuni1840@...il.com>, <netdev@...r.kernel.org>
Subject: [PATCH v1 net 4/4] af_unix: Fix data race around sk->sk_err.

As with sk->sk_shutdown shown in the previous patch, sk->sk_err can be
read locklessly by unix_dgram_sendmsg().

Let's use READ_ONCE() for sk_err as well.

Note that the writer side is marked by commit cc04410af7de ("af_unix:
annotate lockless accesses to sk->sk_err").

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
 net/core/sock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index e3da7eae9338..16584e2dd648 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2749,7 +2749,7 @@ static long sock_wait_for_wmem(struct sock *sk, long timeo)
 			break;
 		if (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN)
 			break;
-		if (sk->sk_err)
+		if (READ_ONCE(sk->sk_err))
 			break;
 		timeo = schedule_timeout(timeo);
 	}
-- 
2.30.2