The bridge netfilter code needs to check for space at the
front of the skb before overwriting; otherwise if skb from
device doesn't have headroom, then it will cause random
memory corruption.
Signed-off-by: Stephen Hemminger <[EMAIL PROTECTED]>
--- linux-2.6.17.9.orig/include/linux/netfilter_bridge.h 2006-08-21
11:39:58.000000000 -0700
+++ linux-2.6.17.9/include/linux/netfilter_bridge.h 2006-08-21
11:40:26.000000000 -0700
@@ -47,18 +47,26 @@
#define BRNF_BRIDGED 0x08
#define BRNF_NF_BRIDGE_PREROUTING 0x10
-
/* Only used in br_forward.c */
-static inline
-void nf_bridge_maybe_copy_header(struct sk_buff *skb)
+static inline 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
--- linux-2.6.17.9.orig/net/bridge/br_forward.c 2006-08-18 09:26:24.000000000
-0700
+++ linux-2.6.17.9/net/bridge/br_forward.c 2006-08-21 11:40:26.000000000
-0700
@@ -43,11 +43,15 @@
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;
-
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