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authorJiri Pirko <jiri@resnulli.us>2013-12-05 16:27:37 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-01-15 15:31:33 -0800
commit61d338f1a9bed6386f0c1e012bd5c521cc4d90a3 (patch)
tree42f6a85d0fbefe8efd40c8caed9b011be5e4a7db /net
parent455dcf9880ec3edf5b19070f23d6b1ebac2f09eb (diff)
br: fix use of ->rx_handler_data in code executed on non-rx_handler path
[ Upstream commit 859828c0ea476b42f3a93d69d117aaba90994b6f ] br_stp_rcv() is reached by non-rx_handler path. That means there is no guarantee that dev is bridge port and therefore simple NULL check of ->rx_handler_data is not enough. There is need to check if dev is really bridge port and since only rcu read lock is held here, do it by checking ->rx_handler pointer. Note that synchronize_net() in netdev_rx_handler_unregister() ensures this approach as valid. Introduced originally by: commit f350a0a87374418635689471606454abc7beaa3a "bridge: use rx_handler_data pointer to store net_bridge_port pointer" Fixed but not in the best way by: commit b5ed54e94d324f17c97852296d61a143f01b227a "bridge: fix RCU races with bridge port" Reintroduced by: commit 716ec052d2280d511e10e90ad54a86f5b5d4dcc2 "bridge: fix NULL pointer deref of br_port_get_rcu" Please apply to stable trees as well. Thanks. RH bugzilla reference: https://bugzilla.redhat.com/show_bug.cgi?id=1025770 Reported-by: Laine Stump <laine@redhat.com> Debugged-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jiri Pirko <jiri@resnulli.us> Acked-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/bridge/br_private.h10
-rw-r--r--net/bridge/br_stp_bpdu.c2
2 files changed, 11 insertions, 1 deletions
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index e14c33b42f75..9a63c4206e4a 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -442,6 +442,16 @@ extern netdev_features_t br_features_recompute(struct net_bridge *br,
extern int br_handle_frame_finish(struct sk_buff *skb);
extern rx_handler_result_t br_handle_frame(struct sk_buff **pskb);
+static inline bool br_rx_handler_check_rcu(const struct net_device *dev)
+{
+ return rcu_dereference(dev->rx_handler) == br_handle_frame;
+}
+
+static inline struct net_bridge_port *br_port_get_check_rcu(const struct net_device *dev)
+{
+ return br_rx_handler_check_rcu(dev) ? br_port_get_rcu(dev) : NULL;
+}
+
/* br_ioctl.c */
extern int br_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
extern int br_ioctl_deviceless_stub(struct net *net, unsigned int cmd, void __user *arg);
diff --git a/net/bridge/br_stp_bpdu.c b/net/bridge/br_stp_bpdu.c
index 8660ea3be705..bdb459d21ad8 100644
--- a/net/bridge/br_stp_bpdu.c
+++ b/net/bridge/br_stp_bpdu.c
@@ -153,7 +153,7 @@ void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
goto err;
- p = br_port_get_rcu(dev);
+ p = br_port_get_check_rcu(dev);
if (!p)
goto err;