From: Pravin B Shelar <pshelar@nicira.com>
Date: Wed, 23 Jan 2013 11:45:42 +0000 (+0000)
Subject: IP_GRE: Fix kernel panic in IP_GRE with GRE csum.
X-Git-Tag: v3.7.8~30
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=70b40e0ec5a61b7c073690c2a2fc1da13b520254;p=thirdparty%2Fkernel%2Fstable.git

IP_GRE: Fix kernel panic in IP_GRE with GRE csum.

[ Upstream commit 5465740ace36f179de5bb0ccb5d46ddeb945e309 ]

Due to IP_GRE GSO support, GRE can recieve non linear skb which
results in panic in case of GRE_CSUM.  Following patch fixes it by
using correct csum API.

Bug introduced in commit 6b78f16e4bdde3936b (gre: add GSO support)

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 7240f8e2dd451..07538a7eab968 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -972,8 +972,12 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
 			ptr--;
 		}
 		if (tunnel->parms.o_flags&GRE_CSUM) {
+			int offset = skb_transport_offset(skb);
+
 			*ptr = 0;
-			*(__sum16 *)ptr = ip_compute_csum((void *)(iph+1), skb->len - sizeof(struct iphdr));
+			*(__sum16 *)ptr = csum_fold(skb_checksum(skb, offset,
+								 skb->len - offset,
+								 0));
 		}
 	}