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net/unix: sk_socket can disappear when state is unlocked

PATCH In review Mark Salyzyn 3 participants 3 messages May 26, 2015 – May 27, 2015

Subsystems (3)
Networking Network drivers Networking unix sockets
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Mark Salyzyn

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PATCH v3 1/1 net/unix: sk_socket can disappear when state is unlocked

got a rare NULL pointer dereference in clear_bit

Signed-off-by Mark Salyzyn <[email protected]>

----
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

---
 net/caif/caif_socket.c | 8 ++++++++
 net/unix/af_unix.c     | 8 ++++++++
 2 files changed, 16 insertions(+)
net/caif/caif_socket.c +8 -0
index 4ec0c80..112ad78 100644
@@ -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);
 	}
 

@@ -373,6 +377,10 @@ static int caif_stream_recvmsg(struct socket *sock, struct msghdr *msg,
 		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);
net/unix/af_unix.c +8 -0
index 5266ea7..0643059 100644
@@ -1880,6 +1880,10 @@ 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);
 	}
 

@@ -1939,6 +1943,10 @@ static int unix_stream_recvmsg(struct socket *sock, struct msghdr *msg,
 		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) {
Signature · 1 line
2.2.0.rc0.207.ga3a616c