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Subject[PATCH] [NETFILTER] bridge: rcu_deref outside read-lock section
Date
As it noted in the comment before the br_handle_frame_finish
function, this function should be called under rcu_read_lock.

The problem callgraph:
br_dev_xmit -> br_nf_pre_routing_finish_bridge_slow ->
-> br_handle_frame_finish -> br_port_get_rcu -> rcu_dereference

And in this case there is no read-lock section.
I have put lock/unlock in br_nf_pre_routing_finish_bridge_slow,
as the only function that calls it(for now) - is br_dev_xmit.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Denis Efremov <yefremov.denis@gmail.com>
---
include/linux/netfilter_bridge.h | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/include/linux/netfilter_bridge.h b/include/linux/netfilter_bridge.h
index 31d2844..ceb048e 100644
--- a/include/linux/netfilter_bridge.h
+++ b/include/linux/netfilter_bridge.h
@@ -79,6 +79,7 @@ extern int br_handle_frame_finish(struct sk_buff *skb);
/* Only used in br_device.c */
static inline int br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
{
+ int res;
struct nf_bridge_info *nf_bridge = skb->nf_bridge;

skb_pull(skb, ETH_HLEN);
@@ -86,7 +87,10 @@ static inline int br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
skb_copy_to_linear_data_offset(skb, -(ETH_HLEN-ETH_ALEN),
skb->nf_bridge->data, ETH_HLEN-ETH_ALEN);
skb->dev = nf_bridge->physindev;
- return br_handle_frame_finish(skb);
+ rcu_read_lock();
+ res = br_handle_frame_finish(skb);
+ rcu_read_unlock();
+ return res;
}

/* This is called by the IP fragmenting code and it ensures there is
--
1.7.7


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