[PATCH 5.4 45/92] net/sched: sch_taprio: ensure to reset/destroy all child qdiscs

[Greg Kroah-Hartman]

From: Davide Caratti <dcaratti@xxxxxxxxxx>

[ Upstream commit 698285da79f5b0b099db15a37ac661ac408c80eb ]

taprio_graft() can insert a NULL element in the array of child qdiscs. As
a consquence, taprio_reset() might not reset child qdiscs completely, and
taprio_destroy() might leak resources. Fix it by ensuring that loops that
iterate over q->qdiscs[] don't end when they find the first NULL item.

Fixes: 44d4775ca518 ("net/sched: sch_taprio: reset child qdiscs before freeing them")
Fixes: 5a781ccbd19e ("tc: Add support for configuring the taprio scheduler")
Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Davide Caratti <dcaratti@xxxxxxxxxx>
Link: https://lore.kernel.org/r/13edef6778fef03adc751582562fba4a13e06d6a.1608240532.git.dcaratti@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/sched/sch_taprio.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1626,7 +1626,7 @@ static void taprio_destroy(struct Qdisc
 	taprio_disable_offload(dev, q, NULL);
 
 	if (q->qdiscs) {
-		for (i = 0; i < dev->num_tx_queues && q->qdiscs[i]; i++)
+		for (i = 0; i < dev->num_tx_queues; i++)
 			qdisc_put(q->qdiscs[i]);
 
 		kfree(q->qdiscs);