linux-kernel - [ 024/110] bridge: fix NULL pointer deref of br_port_get

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20131011193810.333393700@linuxfoundation.org>
Date:	Fri, 11 Oct 2013 12:38:04 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Hong Zhiguo <zhiguohong@...cent.com>,
	Eric Dumazet <edumazet@...gle.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 024/110] bridge: fix NULL pointer deref of br_port_get_rcu

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hong Zhiguo <zhiguohong@...cent.com>

[ Upstream commit 716ec052d2280d511e10e90ad54a86f5b5d4dcc2 ]

The NULL deref happens when br_handle_frame is called between these
2 lines of del_nbp:
	dev->priv_flags &= ~IFF_BRIDGE_PORT;
	/* --> br_handle_frame is called at this time */
	netdev_rx_handler_unregister(dev);

In br_handle_frame the return of br_port_get_rcu(dev) is dereferenced
without check but br_port_get_rcu(dev) returns NULL if:
	!(dev->priv_flags & IFF_BRIDGE_PORT)

Eric Dumazet pointed out the testing of IFF_BRIDGE_PORT is not necessary
here since we're in rcu_read_lock and we have synchronize_net() in
netdev_rx_handler_unregister. So remove the testing of IFF_BRIDGE_PORT
and by the previous patch, make sure br_port_get_rcu is called in
bridging code.

Signed-off-by: Hong Zhiguo <zhiguohong@...cent.com>
Acked-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/bridge/br_private.h |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -183,10 +183,7 @@ struct net_bridge_port
 
 static inline struct net_bridge_port *br_port_get_rcu(const struct net_device *dev)
 {
-	struct net_bridge_port *port =
-			rcu_dereference_rtnl(dev->rx_handler_data);
-
-	return br_port_exists(dev) ? port : NULL;
+	return rcu_dereference(dev->rx_handler_data);
 }
 
 static inline struct net_bridge_port *br_port_get_rtnl(const struct net_device *dev)


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/