From: Eric Dumazet <edumazet@google.com>
Date: Thu, 25 Apr 2013 01:34:55 +0000 (-0700)
Subject: tcp: force a dst refcount when prequeue packet
X-Git-Tag: v3.4.46~26
X-Git-Url: https://git.fsl.cs.sunysb.edu/?a=commitdiff_plain;h=8e1546d7e14ef043ff74070cea0aff55ba2f600c;p=unionfs-2.6.38.y.git

tcp: force a dst refcount when prequeue packet

[ Upstream commit 093162553c33e9479283e107b4431378271c735d ]

Before escaping RCU protected section and adding packet into
prequeue, make sure the dst is refcounted.

Reported-by: Mike Galbraith <bitbucket@online.de>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 2757a115514..8376a6a5df4 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -948,6 +948,7 @@ static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
 	if (sysctl_tcp_low_latency || !tp->ucopy.task)
 		return 0;
 
+	skb_dst_force(skb);
 	__skb_queue_tail(&tp->ucopy.prequeue, skb);
 	tp->ucopy.memory += skb->truesize;
 	if (tp->ucopy.memory > sk->sk_rcvbuf) {