macvtap: fix use after free for skb_array during release

We've clean skb_array in macvtap_put_queue() but still try to pop from
it during macvtap_sock_destruct(). Fix this use after free by moving
the skb array cleanup to macvtap_sock_destruct() instead.

Fixes: 362899b8725b ("macvtap: switch to use skb array")
Reported-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macvtap.c

@@ -275,7 +275,6 @@ static void macvtap_put_queue(struct macvtap_queue *q)
 	rtnl_unlock();
 
 	synchronize_rcu();
-	skb_array_cleanup(&q->skb_array);
 	sock_put(&q->sk);
 }
 
@@ -533,10 +532,8 @@ static void macvtap_sock_write_space(struct sock *sk)
 static void macvtap_sock_destruct(struct sock *sk)
 {
 	struct macvtap_queue *q = container_of(sk, struct macvtap_queue, sk);
-	struct sk_buff *skb;
 
-	while ((skb = skb_array_consume(&q->skb_array)) != NULL)
-		kfree_skb(skb);
+	skb_array_cleanup(&q->skb_array);
 }
 
 static int macvtap_open(struct inode *inode, struct file *file)