From 3a13813e6effcfad5910d47b15b724621b50b878 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Sat, 26 Aug 2006 20:28:30 -0700 Subject: [PATCH] [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 Signed-off-by: David S. Miller --- include/linux/netfilter_bridge.h | 14 ++++++++++++-- net/bridge/br_forward.c | 10 +++++++--- 2 files changed, 19 insertions(+), 5 deletions(-) diff --git a/include/linux/netfilter_bridge.h b/include/linux/netfilter_bridge.h index 10c13dc4665..427c67ff89e 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 6ccd32b3080..864fbbc7b24 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;