path: root/net/bridge
diff options
authorNikolay Aleksandrov <razor@blackwall.org>2015-06-15 20:28:51 +0300
committerDavid S. Miller <davem@davemloft.net>2015-06-18 03:29:47 -0700
commit2dab80a8b486f02222a69daca6859519e05781d9 (patch)
treead530475217a5b3924aba3efa33125c345cf0a80 /net/bridge
parentac0a72a3e6e8d817f60ce4d9a8f3b43dc256d847 (diff)
bridge: fix br_stp_set_bridge_priority race conditions
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>
Diffstat (limited to 'net/bridge')
2 files changed, 3 insertions, 3 deletions
diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index a9a4a1b7863d..8d423bc649b9 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;
diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index 41146872c1b4..7832d07f48f6 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -243,12 +243,13 @@ 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) {
@@ -266,6 +267,7 @@ void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
if (br_is_root_bridge(br) && !wasroot)
+ spin_unlock_bh(&br->lock);
/* called under bridge lock */

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