Merge tag 'v4.4.291' into toradex_vf_4.4-nexttoradex_vf_4.4-nexttoradex_vf_4.4

This is the 4.4.291 stable release

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 260cba93a2cf..65cf129eaad3 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -574,7 +574,10 @@ static int netlink_insert(struct sock *sk, u32 portid)
 
 	/* We need to ensure that the socket is hashed and visible. */
 	smp_wmb();
-	nlk_sk(sk)->bound = portid;
+	/* Paired with lockless reads from netlink_bind(),
+	 * netlink_connect() and netlink_sendmsg().
+	 */
+	WRITE_ONCE(nlk_sk(sk)->bound, portid);
 
 err:
 	release_sock(sk);
@@ -993,7 +996,8 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 	else if (nlk->ngroups < 8*sizeof(groups))
 		groups &= (1UL << nlk->ngroups) - 1;
 
-	bound = nlk->bound;
+	/* Paired with WRITE_ONCE() in netlink_insert() */
+	bound = READ_ONCE(nlk->bound);
 	if (bound) {
 		/* Ensure nlk->portid is up-to-date. */
 		smp_rmb();
@@ -1073,8 +1077,9 @@ static int netlink_connect(struct socket *sock, struct sockaddr *addr,
 
 	/* No need for barriers here as we return to user-space without
 	 * using any of the bound attributes.
+	 * Paired with WRITE_ONCE() in netlink_insert().
 	 */
-	if (!nlk->bound)
+	if (!READ_ONCE(nlk->bound))
 		err = netlink_autobind(sock);
 
 	if (err == 0) {
@@ -1821,7 +1826,8 @@ static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 		dst_group = nlk->dst_group;
 	}
 
-	if (!nlk->bound) {
+	/* Paired with WRITE_ONCE() in netlink_insert() */
+	if (!READ_ONCE(nlk->bound)) {
 		err = netlink_autobind(sock);
 		if (err)
 			goto out;