From: Eric Dumazet Date: Fri, 24 May 2013 05:49:58 +0000 (+0000) Subject: ip_tunnel: fix kernel panic with icmp_dest_unreach X-Git-Tag: v2.6.32.62~96 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=09ef3754dffadf39076a402bc1ca7883c3fa2b73;p=thirdparty%2Fkernel%2Fstable.git ip_tunnel: fix kernel panic with icmp_dest_unreach [ Upstream commit a622260254ee481747cceaaa8609985b29a31565 ] Daniel Petre reported crashes in icmp_dst_unreach() with following call graph: Daniel found a similar problem mentioned in http://lkml.indiana.edu/hypermail/linux/kernel/1007.0/00961.html And indeed this is the root cause : skb->cb[] contains data fooling IP stack. We must clear IPCB in ip_tunnel_xmit() sooner in case dst_link_failure() is called. Or else skb->cb[] might contain garbage from GSO segmentation layer. A similar fix was tested on linux-3.9, but gre code was refactored in linux-3.10. I'll send patches for stable kernels as well. Many thanks to Daniel for providing reports, patches and testing ! Reported-by: Daniel Petre Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Willy Tarreau --- diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c index 860b5c5d88a25..49aa1ad4f74c2 100644 --- a/net/ipv4/ipip.c +++ b/net/ipv4/ipip.c @@ -408,6 +408,7 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev) if (tos&1) tos = old_iph->tos; + memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); if (!dst) { /* NBMA tunnel */ if ((rt = skb_rtable(skb)) == NULL) { @@ -494,7 +495,6 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev) skb->transport_header = skb->network_header; skb_push(skb, sizeof(struct iphdr)); skb_reset_network_header(skb); - memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED); skb_dst_drop(skb);