net: dev_pick_tx() fix
When dev_pick_tx() caches tx queue_index on a socket, we must check
socket dst_entry matches skb one, or risk a crash later, as reported by
Denys Fedorysychenko, if old packets are in flight during a route
change, involving devices with different number of queues.
Bug introduced by commit a4ee3ce3
(net: Use sk_tx_queue_mapping for connected sockets)
Reported-by: Denys Fedorysychenko <nuclearcat@nuclearcat.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 1c8a0ce..92584bf 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1989,8 +1989,12 @@
if (dev->real_num_tx_queues > 1)
queue_index = skb_tx_hash(dev, skb);
- if (sk && sk->sk_dst_cache)
- sk_tx_queue_set(sk, queue_index);
+ if (sk) {
+ struct dst_entry *dst = rcu_dereference(sk->sk_dst_cache);
+
+ if (dst && skb_dst(skb) == dst)
+ sk_tx_queue_set(sk, queue_index);
+ }
}
}