linux-kernel - [PATCH 3.16 177/294] sch_fq_codel: avoid double free on init failure

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Date:   Mon, 06 Nov 2017 23:03:02 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "David S. Miller" <davem@...emloft.net>,
        "Nikolay Aleksandrov" <nikolay@...ulusnetworks.com>
Subject: [PATCH 3.16 177/294] sch_fq_codel: avoid double free on init failure

3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>

commit 30c31d746d0eb458ae327f522bc8e4c44cbea0f0 upstream.

It is very unlikely to happen but the backlogs memory allocation
could fail and will free q->flows, but then ->destroy() will free
q->flows too. For correctness remove the first free and let ->destroy
clean up.

Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Signed-off-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.16: fq_codel used different alloc/free functions]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/sched/sch_fq_codel.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -411,10 +411,8 @@ static int fq_codel_init(struct Qdisc *s
 		if (!q->flows)
 			return -ENOMEM;
 		q->backlogs = fq_codel_zalloc(q->flows_cnt * sizeof(u32));
-		if (!q->backlogs) {
-			fq_codel_free(q->flows);
+		if (!q->backlogs)
 			return -ENOMEM;
-		}
 		for (i = 0; i < q->flows_cnt; i++) {
 			struct fq_codel_flow *flow = q->flows + i;