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Message-Id: <20190919214701.920915648@linuxfoundation.org>
Date: Fri, 20 Sep 2019 00:03:07 +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,
syzbot+d5870a903591faaca4ae@...kaller.appspotmail.com,
Linus Torvalds <torvalds@...ux-foundation.org>,
Jamal Hadi Salim <jhs@...atatu.com>,
Jiri Pirko <jiri@...nulli.us>,
Cong Wang <xiyou.wangcong@...il.com>,
Jiri Pirko <jiri@...lanox.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.3 06/21] net_sched: let qdisc_put() accept NULL pointer
From: Cong Wang <xiyou.wangcong@...il.com>
[ Upstream commit 6efb971ba8edfbd80b666f29de12882852f095ae ]
When tcf_block_get() fails in sfb_init(), q->qdisc is still a NULL
pointer which leads to a crash in sfb_destroy(). Similar for
sch_dsmark.
Instead of fixing each separately, Linus suggested to just accept
NULL pointer in qdisc_put(), which would make callers easier.
(For sch_dsmark, the bug probably exists long before commit
6529eaba33f0.)
Fixes: 6529eaba33f0 ("net: sched: introduce tcf block infractructure")
Reported-by: syzbot+d5870a903591faaca4ae@...kaller.appspotmail.com
Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Jamal Hadi Salim <jhs@...atatu.com>
Cc: Jiri Pirko <jiri@...nulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
Acked-by: Jiri Pirko <jiri@...lanox.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
net/sched/sch_generic.c | 3 +++
1 file changed, 3 insertions(+)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -985,6 +985,9 @@ 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;
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