linux-kernel - [PATCH 4.4 273/312] qdisc: fix a module refcount leak in qdisc_create

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Date:   Fri,  8 May 2020 14:34:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        John Fastabend <john.r.fastabend@...el.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 273/312] qdisc: fix a module refcount leak in qdisc_create_dflt()

From: Eric Dumazet <edumazet@...gle.com>

commit 166ee5b87866de07a3e56c1b757f2b5cabba72a5 upstream.

Should qdisc_alloc() fail, we must release the module refcount
we got right before.

Fixes: 6da7c8fcbcbd ("qdisc: allow setting default queuing discipline")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Acked-by: John Fastabend <john.r.fastabend@...el.com>
Acked-by: John Fastabend <john.r.fastabend@...el.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/sched/sch_generic.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -626,18 +626,19 @@ struct Qdisc *qdisc_create_dflt(struct n
 	struct Qdisc *sch;
 
 	if (!try_module_get(ops->owner))
-		goto errout;
+		return NULL;
 
 	sch = qdisc_alloc(dev_queue, ops);
-	if (IS_ERR(sch))
-		goto errout;
+	if (IS_ERR(sch)) {
+		module_put(ops->owner);
+		return NULL;
+	}
 	sch->parent = parentid;
 
 	if (!ops->init || ops->init(sch, NULL) == 0)
 		return sch;
 
 	qdisc_destroy(sch);
-errout:
 	return NULL;
 }
 EXPORT_SYMBOL(qdisc_create_dflt);