[NET_SCHED]: Fix filter double free

cbq and atm destroy their filters twice when destroying inner classes
during qdisc destruction.

Reported-and-tested-by: Strobl Anton <a.strobl@aws-it.at>

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 3 deletions

diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index a294542cb8e4..ee2d5967d109 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -1748,10 +1748,12 @@ cbq_destroy(struct Qdisc* sch)
          * classes from root to leafs which means that filters can still
          * be bound to classes which have been destroyed already. --TGR '04
          */
-        for (h = 0; h < 16; h++)
-                for (cl = q->classes[h]; cl; cl = cl->next)
+        for (h = 0; h < 16; h++) {
+                for (cl = q->classes[h]; cl; cl = cl->next) {
                         tcf_destroy_chain(cl->filter_list);
-
+                        cl->filter_list = NULL;
+                }
+        }
         for (h = 0; h < 16; h++) {
                 struct cbq_class *next;