| From | Jiri Slaby <> | Subject | [PATCH 3.12 55/83] tcp: tcp_make_synack() should clear skb->tstamp | Date | Mon, 27 Apr 2015 23:32:26 +0200 |
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From: Eric Dumazet <edumazet@google.com>
3.12-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit b50edd7812852d989f2ef09dcfc729690f54a42d ]
I noticed tcpdump was giving funky timestamps for locally generated SYNACK messages on loopback interface.
11:42:46.938990 IP 127.0.0.1.48245 > 127.0.0.2.23850: S 945476042:945476042(0) win 43690 <mss 65495,nop,nop,sackOK,nop,wscale 7>
20:28:58.502209 IP 127.0.0.2.23850 > 127.0.0.1.48245: S 3160535375:3160535375(0) ack 945476043 win 43690 <mss 65495,nop,nop,sackOK,nop,wscale 7>
This is because we need to clear skb->tstamp before entering lower stack, otherwise net_timestamp_check() does not set skb->tstamp.
Fixes: 7faee5c0d514 ("tcp: remove TCP_SKB_CB(skb)->when") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- net/ipv4/tcp_output.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 56db79dbc633..72d11b4593c8 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2782,6 +2782,8 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, } #endif + /* Do not fool tcpdump (if any), clean our debris */ + skb->tstamp.tv64 = 0; return skb; } EXPORT_SYMBOL(tcp_make_synack); -- 2.3.5
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