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authorMichael Braun <michael-dev@fami-braun.de>2010-03-16 00:26:22 -0700
committerDavid S. Miller <davem@davemloft.net>2010-03-16 00:26:22 -0700
commit7f7708f0055e49e331f267700aa8b2ee879f004c (patch)
tree385da7d1b722232c3c9003af52079318aa51326e /net/bridge/br_private.h
parent0821ec55bb1382dd3b9476dc15d5dbbb19f0c3fd (diff)
bridge: Fix br_forward crash in promiscuous mode
From: Michael Braun <michael-dev@fami-braun.de> bridge: Fix br_forward crash in promiscuous mode It's a linux-next kernel from 2010-03-12 on an x86 system and it OOPs in the bridge module in br_pass_frame_up (called by br_handle_frame_finish) because brdev cannot be dereferenced (its set to a non-null value). Adding some BUG_ON statements revealed that BR_INPUT_SKB_CB(skb)->brdev == br-dev (as set in br_handle_frame_finish first) only holds until br_forward is called. The next call to br_pass_frame_up then fails. Digging deeper it seems that br_forward either frees the skb or passes it to NF_HOOK which will in turn take care of freeing the skb. The same is holds for br_pass_frame_ip. So it seems as if two independent skb allocations are required. As far as I can see, commit b33084be192ee1e347d98bb5c9e38a53d98d35e2 ("bridge: Avoid unnecessary clone on forward path") removed skb duplication and so likely causes this crash. This crash does not happen on 2.6.33. I've therefore modified br_forward the same way br_flood has been modified so that the skb is not freed if skb0 is going to be used and I can confirm that the attached patch resolves the issue for me. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/bridge/br_private.h')
-rw-r--r--net/bridge/br_private.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index fef0384e3c0..bfb8feb310a 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -252,7 +252,7 @@ extern void br_deliver(const struct net_bridge_port *to,
struct sk_buff *skb);
extern int br_dev_queue_push_xmit(struct sk_buff *skb);
extern void br_forward(const struct net_bridge_port *to,
- struct sk_buff *skb);
+ struct sk_buff *skb, struct sk_buff *skb0);
extern int br_forward_finish(struct sk_buff *skb);
extern void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb);
extern void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,