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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
        Davide Caratti <dcaratti@redhat.com>
Subject: [PATCH 5.4 45/92] net/sched: sch_taprio: ensure to reset/destroy all child qdiscs
Date:   Mon, 11 Jan 2021 14:01:49 +0100
Message-Id: <20210111130041.315198350@linuxfoundation.org>
In-Reply-To: <20210111130039.165470698@linuxfoundation.org>
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From: Davide Caratti <dcaratti@redhat.com>

[ 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@kernel.org>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Link: https://lore.kernel.org/r/13edef6778fef03adc751582562fba4a13e06d6a.1608240532.git.dcaratti@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 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);