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authorStephen Hemminger <shemminger@osdl.org>2006-08-26 20:28:30 -0700
committerDavid S. Miller <davem@davemloft.net>2006-08-26 20:28:30 -0700
commit3a13813e6effcfad5910d47b15b724621b50b878 (patch)
tree30aaf88578ee23b0a1c0f90e7ee1100244d62415
parent8dbc16033e35c7443cd56cb5ba308bb19cb7b469 (diff)
[BRIDGE] netfilter: memory corruption fix
The bridge-netfilter code will overwrite memory if there is not headroom in the skb to save the header. This first showed up when using Xen with sky2 driver that doesn't allocate the extra space. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/linux/netfilter_bridge.h14
-rw-r--r--net/bridge/br_forward.c10
2 files changed, 19 insertions, 5 deletions
diff --git a/include/linux/netfilter_bridge.h b/include/linux/netfilter_bridge.h
index 10c13dc4665b..427c67ff89e9 100644
--- a/include/linux/netfilter_bridge.h
+++ b/include/linux/netfilter_bridge.h
@@ -48,15 +48,25 @@ enum nf_br_hook_priorities {
/* Only used in br_forward.c */
static inline
-void nf_bridge_maybe_copy_header(struct sk_buff *skb)
+int nf_bridge_maybe_copy_header(struct sk_buff *skb)
{
+ int err;
+
if (skb->nf_bridge) {
if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
+ err = skb_cow(skb, 18);
+ if (err)
+ return err;
memcpy(skb->data - 18, skb->nf_bridge->data, 18);
skb_push(skb, 4);
- } else
+ } else {
+ err = skb_cow(skb, 16);
+ if (err)
+ return err;
memcpy(skb->data - 16, skb->nf_bridge->data, 16);
+ }
}
+ return 0;
}
/* This is called by the IP fragmenting code and it ensures there is
diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index 6ccd32b30809..864fbbc7b24d 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -40,11 +40,15 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
else {
#ifdef CONFIG_BRIDGE_NETFILTER
/* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
- nf_bridge_maybe_copy_header(skb);
+ if (nf_bridge_maybe_copy_header(skb))
+ kfree_skb(skb);
+ else
#endif
- skb_push(skb, ETH_HLEN);
+ {
+ skb_push(skb, ETH_HLEN);
- dev_queue_xmit(skb);
+ dev_queue_xmit(skb);
+ }
}
return 0;