net: preserve IP control block during GSO segmentation

net: preserve IP control block during GSO segmentation

Orabug: 24469379

[ Upstream commit 9207f9d45b0ad071baa128e846d7e7ed85016df3 ]

Skb_gso_segment() uses skb control block during segmentation.
This patch adds 32-bytes room for previous control block which
will be copied into all resulting segments.

This patch fixes kernel crash during fragmenting forwarded packets.
Fragmentation requires valid IP CB in skb for clearing ip options.
Also patch removes custom save/restore in ovs code, now it's redundant.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Link: http://lkml.kernel.org/r/CALYGNiP-0MZ-FExV2HutTvE9U-QQtkKSoE--KN=JQE5STYsjAA@mail.gmail.com
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit abefd1b4087b9b5e83e7b4e7689f8b8e3cb2899c)

Signed-off-by: Dan Duval <dan.duval@oracle.com>
Signed-off-by: Ajaykumar Hotchandani <ajaykumar.hotchandani@oracle.com>