[PATCH] tcp: Modify the condition for the first skb to collapse

[Jun Chen <jun.d.chen@intel.com>]

When search the first skb to collapse,the condition of overlap to the next one have been
reached,but the start is less than TCP_SKB_CB(skb)->seq at this time, then followed process
will trigger the BUG_ON of the offset(start - TCP_SKB_CB(skb)->seq).
So this patch add one check (! before(start,TCP_SKB_CB(skb)->seq)) to avoid this ipanic.

Signed-off-by: Chen Jun <jun.d.chen@intel.com>
---
 net/ipv4/tcp_input.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9c62257..4c745c5 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4465,7 +4465,8 @@ restart:
 		 *   overlaps to the next one.
 		 */
 		if (!tcp_hdr(skb)->syn && !tcp_hdr(skb)->fin &&
-		    (tcp_win_from_space(skb->truesize) > skb->len ||
+			((tcp_win_from_space(skb->truesize) > skb->len &&
+			!before(start, TCP_SKB_CB(skb)->seq)) ||
 		     before(TCP_SKB_CB(skb)->seq, start))) {
 			end_of_skbs = false;
 			break;
-- 
1.7.4.1