[NETNS]: The ip6_fib_timer can work with garbage on net namespace stop.

The del_timer() function doesn't guarantee, that the timer callback
is not active by the time it exits.

Thus, the fib6_net_exit() may kfree() all the data, that is required
by the fib6_run_gc(). The race window is tiny, but slab poisoning can
trigger this bug.

Using del_timer_sync() will cure this.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 50f3f8f8a59b3bba58fad607db386a6d9c94774d..1ee4fa17c12959a14c835663abdb81ce349f8de4 100644 (file)
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1543,7 +1543,7 @@ out_timer:
 static void fib6_net_exit(struct net *net)
 {
        rt6_ifdown(net, NULL);
-       del_timer(net->ipv6.ip6_fib_timer);
+       del_timer_sync(net->ipv6.ip6_fib_timer);
        kfree(net->ipv6.ip6_fib_timer);
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
        kfree(net->ipv6.fib6_local_tbl);