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authorNikolay Aleksandrov <razor@blackwall.org>2015-06-15 20:28:51 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-07-10 10:40:20 -0700
commit019b1332afd4dc4c80fa83379866d01984933694 (patch)
tree935306864954188f83ac351da5781451380903a7
parent80cbc4a31be6abe812cdbd81d4b98e4d7771c7fa (diff)
bridge: fix br_stp_set_bridge_priority race conditions
[ Upstream commit 2dab80a8b486f02222a69daca6859519e05781d9 ] After the ->set() spinlocks were removed br_stp_set_bridge_priority was left running without any protection when used via sysfs. It can race with port add/del and could result in use-after-free cases and corrupted lists. Tested by running port add/del in a loop with stp enabled while setting priority in a loop, crashes are easily reproducible. The spinlocks around sysfs ->set() were removed in commit: 14f98f258f19 ("bridge: range check STP parameters") There's also a race condition in the netlink priority support that is fixed by this change, but it was introduced recently and the fixes tag covers it, just in case it's needed the commit is: af615762e972 ("bridge: add ageing_time, stp_state, priority over netlink") Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org> Fixes: 14f98f258f19 ("bridge: range check STP parameters") Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/bridge/br_ioctl.c2
-rw-r--r--net/bridge/br_stp_if.c4
2 files changed, 3 insertions, 3 deletions
diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index cd8c3a44ab7d..b73eaba85667 100644
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c
@@ -247,9 +247,7 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
return -EPERM;
- spin_lock_bh(&br->lock);
br_stp_set_bridge_priority(br, args[1]);
- spin_unlock_bh(&br->lock);
return 0;
case BRCTL_SET_PORT_PRIORITY:
diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index 656a6f3e40de..886f6d6dc48a 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -241,12 +241,13 @@ bool br_stp_recalculate_bridge_id(struct net_bridge *br)
return true;
}
-/* called under bridge lock */
+/* Acquires and releases bridge lock */
void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
{
struct net_bridge_port *p;
int wasroot;
+ spin_lock_bh(&br->lock);
wasroot = br_is_root_bridge(br);
list_for_each_entry(p, &br->port_list, list) {
@@ -264,6 +265,7 @@ void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
br_port_state_selection(br);
if (br_is_root_bridge(br) && !wasroot)
br_become_root_bridge(br);
+ spin_unlock_bh(&br->lock);
}
/* called under bridge lock */