[ 32/61] IP_GRE: Fix kernel panic in IP_GRE with GRE csum.

Greg Kroah-Hartman
2013-02-12T20:36:00Z

From: Pravin B Shelar <pshelar@nicira.com>

[ 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>
---
net/ipv4/ip_gre.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -972,8 +972,12 @@ static netdev_tx_t ipgre_tunnel_xmit(str
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));
}
}