This is a note to let you know that I've just added the patch titled

    ip_tunnel: fix kernel panic with icmp_dest_unreach

to the 3.4-stable tree which can be found at:
    
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ip_tunnel-fix-kernel-panic-with-icmp_dest_unreach.patch
and it can be found in the queue-3.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.


>From b7722eeecedff96f5e4adb8cb25cd03ef5c364d4 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <[email protected]>
Date: Fri, 24 May 2013 05:49:58 +0000
Subject: ip_tunnel: fix kernel panic with icmp_dest_unreach

From: Eric Dumazet <[email protected]>

[ 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 <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 net/ipv4/ip_gre.c |    2 +-
 net/ipv4/ipip.c   |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -722,6 +722,7 @@ static netdev_tx_t ipgre_tunnel_xmit(str
                tiph = &tunnel->parms.iph;
        }
 
+       memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
        if ((dst = tiph->daddr) == 0) {
                /* NBMA tunnel */
 
@@ -865,7 +866,6 @@ static netdev_tx_t ipgre_tunnel_xmit(str
        skb_reset_transport_header(skb);
        skb_push(skb, gre_hlen);
        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);
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -448,6 +448,7 @@ static netdev_tx_t ipip_tunnel_xmit(stru
        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) {
@@ -530,7 +531,6 @@ static netdev_tx_t ipip_tunnel_xmit(stru
        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);


Patches currently in stable-queue which might be from [email protected] are

queue-3.4/ipv6-fix-possible-crashes-in-ip6_cork_release.patch
queue-3.4/tcp-xps-fix-reordering-issues.patch
queue-3.4/ip_tunnel-fix-kernel-panic-with-icmp_dest_unreach.patch
queue-3.4/tcp-fix-tcp_md5_hash_skb_data.patch
queue-3.4/net-force-a-reload-of-first-item-in-hlist_nulls_for_each_entry_rcu.patch
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