[PATCH 3.16.y-ckt 37/71] unix/caif: sk_socket can disappear when state is unlocked

[Luis Henriques]

3.16.7-ckt14 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mark Salyzyn <salyzyn at android.com>

commit b48732e4a48d80ed4a14812f0bab09560846514e upstream.

got a rare NULL pointer dereference in clear_bit

Signed-off-by: Mark Salyzyn <salyzyn at android.com>
Acked-by: Hannes Frederic Sowa <hannes at stressinduktion.org>
----
v2: switch to sock_flag(sk, SOCK_DEAD) and added net/caif/caif_socket.c
v3: return -ECONNRESET in upstream caller of wait function for SOCK_DEAD
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/caif/caif_socket.c | 8 ++++++++
 net/unix/af_unix.c     | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c
index 5e078a0b2455..a1a5e852be54 100644
--- a/net/caif/caif_socket.c
+++ b/net/caif/caif_socket.c
@@ -330,6 +330,10 @@ static long caif_stream_data_wait(struct sock *sk, long timeo)
 		release_sock(sk);
 		timeo = schedule_timeout(timeo);
 		lock_sock(sk);
+
+		if (sock_flag(sk, SOCK_DEAD))
+			break;
+
 		clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
 	}
 
@@ -374,6 +378,10 @@ static int caif_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 		struct sk_buff *skb;
 
 		lock_sock(sk);
+		if (sock_flag(sk, SOCK_DEAD)) {
+			err = -ECONNRESET;
+			goto unlock;
+		}
 		skb = skb_dequeue(&sk->sk_receive_queue);
 		caif_check_flow_release(sk);
 
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index e96884380732..8232118b3f82 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1899,6 +1899,10 @@ static long unix_stream_data_wait(struct sock *sk, long timeo,
 		unix_state_unlock(sk);
 		timeo = freezable_schedule_timeout(timeo);
 		unix_state_lock(sk);
+
+		if (sock_flag(sk, SOCK_DEAD))
+			break;
+
 		clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
 	}
 
@@ -1963,6 +1967,10 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 		struct sk_buff *skb, *last;
 
 		unix_state_lock(sk);
+		if (sock_flag(sk, SOCK_DEAD)) {
+			err = -ECONNRESET;
+			goto unlock;
+		}
 		last = skb = skb_peek(&sk->sk_receive_queue);
 again:
 		if (skb == NULL) {