net: add a temporary sanity check in skb_orphan()

David suggested to add a BUG_ON() to catch if some layer
sets skb->sk pointer without a corresponding destructor.

As skb can sit in a queue, it's mandatory to make sure the
socket cannot disappear, and it's usually done by taking a
reference on the socket, then releasing it from the skb
destructor.

This patch is a follow-up to commit c34a761231b5
("net: skb_orphan() changes") and will be reverted after
catching all possible offenders if any.

Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index a95547a..d48de68 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1809,6 +1809,8 @@ static inline void skb_orphan(struct sk_buff *skb)
                skb->destructor(skb);
                skb->destructor = NULL;
                skb->sk         = NULL;
+       } else {
+               BUG_ON(skb->sk);
        }
 }