Merge branch 'af_unix-OOB-fixes'

Kuniyuki Iwashima says: ==================== af_unix: Fix some OOB implementation. This series fixes some data-races and adds a missing feature around the commit 314001f ("af_unix: Add OOB support"). Changelog: - v3: - Add the first patch - v2: https://lore.kernel.org/netdev/[email protected]/ - Add READ_ONCE() to avoid a race reported by KCSAN (Eric) - Add IS_ENABLED(CONFIG_AF_UNIX_OOB) (Shoaib) - v1: https://lore.kernel.org/netdev/[email protected]/ ==================== Signed-off-by: David S. Miller <[email protected]>
raspberrypi · Mar 18, 2022 · 9905eed · 9905eed
2 parents 4219196 + d9a232d
commit 9905eed
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Showing 2 changed files with 12 additions and 10 deletions.
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
@@ -2084,7 +2084,7 @@ static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other
 	if (ousk->oob_skb)
 		consume_skb(ousk->oob_skb);
 
-	ousk->oob_skb = skb;
+	WRITE_ONCE(ousk->oob_skb, skb);
 
 	scm_stat_add(other, skb);
 	skb_queue_tail(&other->sk_receive_queue, skb);
@@ -2602,9 +2602,8 @@ static int unix_stream_recv_urg(struct unix_stream_read_state *state)
 
 	oob_skb = u->oob_skb;
 
-	if (!(state->flags & MSG_PEEK)) {
-		u->oob_skb = NULL;
-	}
+	if (!(state->flags & MSG_PEEK))
+		WRITE_ONCE(u->oob_skb, NULL);
 
 	unix_state_unlock(sk);
 
@@ -2639,7 +2638,7 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 				skb = NULL;
 			} else if (sock_flag(sk, SOCK_URGINLINE)) {
 				if (!(flags & MSG_PEEK)) {
-					u->oob_skb = NULL;
+					WRITE_ONCE(u->oob_skb, NULL);
 					consume_skb(skb);
 				}
 			} else if (!(flags & MSG_PEEK)) {
@@ -3094,11 +3093,10 @@ static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 	case SIOCATMARK:
 		{
 			struct sk_buff *skb;
-			struct unix_sock *u = unix_sk(sk);
 			int answ = 0;
 
 			skb = skb_peek(&sk->sk_receive_queue);
-			if (skb && skb == u->oob_skb)
+			if (skb && skb == READ_ONCE(unix_sk(sk)->oob_skb))
 				answ = 1;
 			err = put_user(answ, (int __user *)arg);
 		}
@@ -3139,6 +3137,10 @@ static __poll_t unix_poll(struct file *file, struct socket *sock, poll_table *wa
 		mask |= EPOLLIN | EPOLLRDNORM;
 	if (sk_is_readable(sk))
 		mask |= EPOLLIN | EPOLLRDNORM;
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+	if (READ_ONCE(unix_sk(sk)->oob_skb))
+		mask |= EPOLLPRI;
+#endif
 
 	/* Connection-based need to check for termination and startup */
 	if ((sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) &&

diff --git a/tools/testing/selftests/net/af_unix/test_unix_oob.c b/tools/testing/selftests/net/af_unix/test_unix_oob.c
@@ -218,10 +218,10 @@ main(int argc, char **argv)
 
 	/* Test 1:
 	 * veriyf that SIGURG is
-	 * delivered and 63 bytes are
-	 * read and oob is '@'
+	 * delivered, 63 bytes are
+	 * read, oob is '@', and POLLPRI works.
 	 */
-	wait_for_data(pfd, POLLIN | POLLPRI);
+	wait_for_data(pfd, POLLPRI);
 	read_oob(pfd, &oob);
 	len = read_data(pfd, buf, 1024);
 	if (!signal_recvd || len != 63 || oob != '@') {