af_unix: take receive queue lock while appending new skb

While possibly in future we don't necessarily need to use
sk_buff_head.lock this is a rather larger change, as it affects the
af_unix fd garbage collector, diag and socket cleanups. This is too much
for a stable patch.

For the time being grab sk_buff_head.lock without disabling bh and irqs,
so don't use locked skb_queue_tail.

Fixes: 869e7c62486e ("net: af_unix: implement stream sendpage support")
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Reported-by: Eric Dumazet <edumazet@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index a8352db5c5b5..955ec152cb71 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1813,8 +1813,11 @@ alloc_skb:
         skb->truesize += size;
         atomic_add(size, &sk->sk_wmem_alloc);
 
-        if (newskb)
+        if (newskb) {
+                spin_lock(&other->sk_receive_queue.lock);
                 __skb_queue_tail(&other->sk_receive_queue, newskb);
+                spin_unlock(&other->sk_receive_queue.lock);
+        }
 
         unix_state_unlock(other);
         mutex_unlock(&unix_sk(other)->readlock);