[PATCH 3.14 10/44] unix/caif: sk_socket can disappear when state is unlocked

Greg Kroah-Hartman
2015-06-19T20:50:08Z

From: Mark Salyzyn <salyzyn@android.com>

[ 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/caif/caif_socket.c | 8 ++++++++
net/unix/af_unix.c | 8 ++++++++
2 files changed, 16 insertions(+)

--- a/net/caif/caif_socket.c
+++ b/net/caif/caif_socket.c
@@ -332,6 +332,10 @@ static long caif_stream_data_wait(struct
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);
}

@@ -376,6 +380,10 @@ static int caif_stream_recvmsg(struct ki
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);

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1893,6 +1893,10 @@ static long unix_stream_data_wait(struct
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);
}

@@ -1957,6 +1961,10 @@ static int unix_stream_recvmsg(struct ki
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) {