From patchwork Mon Aug 13 22:47:42 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [NETFILTER] bridge: rcu_deref outside read-lock section Date: Mon, 13 Aug 2012 12:47:42 -0000 From: Denis Efremov X-Patchwork-Id: 177143 Message-Id: <1344898062-23633-1-git-send-email-yefremov.denis@gmail.com> To: Pablo Neira Ayuso Cc: Denis Efremov , Patrick McHardy , netfilter-devel@vger.kernel.org, netfilter@vger.kernel.org, coreteam@netfilter.org, linux-kernel@vger.kernel.org, ldv-project@ispras.ru 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 --- 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