1 files changed, 25 insertions, 9 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 6e5c14309fb8..98d8453eee27 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -419,11 +419,13 @@ void netlink_table_ungrab(void)
 static inline void
 netlink_lock_table(void)
 {
+	unsigned long flags;
+
 	/* read_lock() synchronizes us to netlink_table_grab */
 
-	read_lock(&nl_table_lock);
+	read_lock_irqsave(&nl_table_lock, flags);
 	atomic_inc(&nl_table_users);
-	read_unlock(&nl_table_lock);
+	read_unlock_irqrestore(&nl_table_lock, flags);
 }
 
 static inline void
@@ -556,7 +558,10 @@ 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);
@@ -971,7 +976,8 @@ 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();
@@ -983,7 +989,8 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 	if (nlk->netlink_bind && groups) {
 		int group;
 
-		for (group = 0; group < nlk->ngroups; group++) {
+		/* nl_groups is a u32, so cap the maximum groups we can bind */
+		for (group = 0; group < BITS_PER_TYPE(u32); group++) {
 			if (!test_bit(group, &groups))
 				continue;
 			err = nlk->netlink_bind(net, group + 1);
@@ -1002,7 +1009,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 			netlink_insert(sk, nladdr->nl_pid) :
 			netlink_autobind(sock);
 		if (err) {
-			netlink_undo_bind(nlk->ngroups, groups, sk);
+			netlink_undo_bind(BITS_PER_TYPE(u32), groups, sk);
 			return err;
 		}
 	}
@@ -1050,8 +1057,9 @@ 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) {
@@ -1776,6 +1784,11 @@ static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 	if (msg->msg_flags&MSG_OOB)
 		return -EOPNOTSUPP;
 
+	if (len == 0) {
+		pr_warn_once("Zero length message leads to an empty skb\n");
+		return -ENODATA;
+	}
+
 	err = scm_send(sock, msg, &scm, true);
 	if (err < 0)
 		return err;
@@ -1798,7 +1811,8 @@ 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;
@@ -2382,13 +2396,15 @@ int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
 		/* errors reported via destination sk->sk_err, but propagate
 		 * delivery errors if NETLINK_BROADCAST_ERROR flag is set */
 		err = nlmsg_multicast(sk, skb, exclude_portid, group, flags);
+		if (err == -ESRCH)
+			err = 0;
 	}
 
 	if (report) {
 		int err2;
 
 		err2 = nlmsg_unicast(sk, skb, portid);
-		if (!err || err == -ESRCH)
+		if (!err)
 			err = err2;
 	}