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author | Jiri Pirko <jiri@resnulli.us> | 2013-12-05 16:27:37 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-11-21 09:22:54 -0800 |
commit | a4ad890a7e7fac8177d93a4345c7a239339840ed (patch) | |
tree | 1a212b616b9db67138176bd85a1b915a35155b62 /net | |
parent | 5eb4491e33b498f05bf51c75ed4abc46a5fccaba (diff) | |
download | lwn-a4ad890a7e7fac8177d93a4345c7a239339840ed.tar.gz lwn-a4ad890a7e7fac8177d93a4345c7a239339840ed.zip |
br: fix use of ->rx_handler_data in code executed on non-rx_handler path
commit 859828c0ea476b42f3a93d69d117aaba90994b6f upstream.
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>
Cc: Andrew Collins <bsderandrew@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r-- | net/bridge/br_private.h | 10 | ||||
-rw-r--r-- | net/bridge/br_stp_bpdu.c | 2 |
2 files changed, 11 insertions, 1 deletions
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index e696833a31b5..11ab6628027a 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -429,6 +429,16 @@ 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; |