commit 3b11775033dc87c3d161996c54507b15ba26414a
author Eric Dumazet <edumazet@google.com> Thu Nov 02 12:30:25 2017 -0700
committer David S. Miller <davem@davemloft.net> Fri Nov 03 14:29:01 2017 +0900
tree 01e52ff98514d77a36116f02f3745b1bce20d519
parent 25dd169aea6553aea548197a5d4580bbdeda1c85

tcp: do not mangle skb->cb[] in tcp_make_synack()

Christoph Paasch sent a patch to address the following issue :

tcp_make_synack() is leaving some TCP private info in skb->cb[],
then send the packet by other means than tcp_transmit_skb()

tcp_transmit_skb() makes sure to clear skb->cb[] to not confuse
IPv4/IPV6 stacks, but we have no such cleanup for SYNACK.

tcp_make_synack() should not use tcp_init_nondata_skb() :

tcp_init_nondata_skb() really should be limited to skbs put in write/rtx
queues (the ones that are only sent via tcp_transmit_skb())

This patch fixes the issue and should even save few cpu cycles ;)

Fixes: 971f10eca186 ("tcp: better TCP_SKB_CB layout to reduce cache line misses")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Christoph Paasch <cpaasch@apple.com>
Reviewed-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: David S. Miller <davem@davemloft.net>