unix/caif: sk_socket can disappear when state is unlocked

[ Upstream commit b48732e4a48d80ed4a14812f0bab09560846514e ]

got a rare NULL pointer dereference in clear_bit

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Acked-by: Hannes Frederic Sowa <hannes@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@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c
index 7eed9eb..7e4b4b4 100644 (file)
--- a/net/caif/caif_socket.c
+++ b/net/caif/caif_socket.c
@@ -366,6 +366,10 @@ 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);
        }
 
@@ -410,6 +414,10 @@ 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 8705ee3..9b1f371 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1870,6 +1870,10 @@ static long unix_stream_data_wait(struct sock *sk, long timeo)
                unix_state_unlock(sk);
                timeo = schedule_timeout(timeo);
                unix_state_lock(sk);
+
+               if (sock_flag(sk, SOCK_DEAD))
+                       break;
+
                clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
        }
 
@@ -1930,6 +1934,10 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
                struct sk_buff *skb;
 
                unix_state_lock(sk);
+               if (sock_flag(sk, SOCK_DEAD)) {
+                       err = -ECONNRESET;
+                       goto unlock;
+               }
                skb = skb_peek(&sk->sk_receive_queue);
                if (skb == NULL) {
                        unix_sk(sk)->recursion_level = 0;