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 <daniel.petre@rcs-rds.ro>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index d55110e..5f28fab 100644 (file)
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -716,6 +716,7 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
                tiph = &tunnel->parms.iph;
        }
 
                tiph = &tunnel->parms.iph;
        }
 

+       memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));

        if ((dst = tiph->daddr) == 0) {
                /* NBMA tunnel */
 
        if ((dst = tiph->daddr) == 0) {
                /* NBMA tunnel */
 


@@ -851,7 +852,6 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
        skb_reset_transport_header(skb);
        skb_push(skb, gre_hlen);
        skb_reset_network_header(skb);
        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);
        IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
                              IPSKB_REROUTED);
        skb_dst_drop(skb);

diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 17ad951..5dc5137 100644 (file)
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -448,6 +448,7 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
        if (tos & 1)
                tos = old_iph->tos;
 
        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) {
        if (!dst) {
                /* NBMA tunnel */
                if ((rt = skb_rtable(skb)) == NULL) {


@@ -531,7 +532,6 @@ 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);
        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);
        IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
                              IPSKB_REROUTED);
        skb_dst_drop(skb);