From: Eric Dumazet <edumazet@google.com>
Date: Wed, 5 Mar 2014 22:08:38 +0000 (-0800)
Subject: tcp: do not leak non zero tstamp in output packets
X-Git-Tag: v3.15-rc1~113^2~212
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=219626924222b6b41bf2264896b34a6abaaeecf0;p=linux.git

tcp: do not leak non zero tstamp in output packets

Usage of skb->tstamp should remain private to TCP stack
(only set on packets on write queue, not on cloned ones)

Otherwise, packets given to loopback interface with a non null tstamp
can confuse netif_rx() / net_timestamp_check()

Other possibility would be to clear tstamp in loopback_xmit(),
as done in skb_scrub_packet()

Fixes: 740b0f1841f6 ("tcp: switch rtt estimations to usec resolution")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index a02c884d4321..bc0fb0fc7552 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -882,6 +882,8 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 			skb = skb_clone(skb, gfp_mask);
 		if (unlikely(!skb))
 			return -ENOBUFS;
+		/* Our usage of tstamp should remain private */
+		skb->tstamp.tv64 = 0;
 	}
 
 	inet = inet_sk(sk);