[PATCH 4.19 48/49] net/sched: move NULL ptr check to qdisc_put() too

Greg Kroah-Hartman
2022-06-30T14:03:14Z

From: Diederik de Haas <didi.debian@cknow.org>

In commit 92833e8b5db6c209e9311ac8c6a44d3bf1856659 titled
"net: sched: rename qdisc_destroy() to qdisc_put()" part of the
functionality of qdisc_destroy() was moved into a (for linux-4.19.y)
new function qdisk_put(), and the previous calls to qdisc_destroy()
were changed to qdisk_put().
This made it similar to f.e. 5.10.y and current master.

There was one part of qdisc_destroy() not moved over to qdisc_put() and
that was the check for a NULL pointer, causing oopses.
(See upstream commit: 6efb971ba8edfbd80b666f29de12882852f095ae)
This patch fixes that.

Fixes: 92833e8b5db6c209e9311ac8c6a44d3bf1856659
Reported-by: Thorsten Glaser <tg@mirbsd.de>
Link: https://bugs.debian.org/1013299
Signed-off-by: Diederik de Haas <didi.debian@cknow.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sched/sch_generic.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -970,8 +970,6 @@ static void qdisc_destroy(struct Qdisc *
const struct Qdisc_ops *ops;
struct sk_buff *skb, *tmp;

- if (!qdisc)
- return;
ops = qdisc->ops;

#ifdef CONFIG_NET_SCHED
@@ -1003,6 +1001,9 @@ static void qdisc_destroy(struct Qdisc *

void qdisc_put(struct Qdisc *qdisc)
{
+ if (!qdisc)
+ return;
+
if (qdisc->flags & TCQ_F_BUILTIN ||
!refcount_dec_and_test(&qdisc->refcnt))
return;