From: Diederik de Haas <didi.debian@xxxxxxxxx> 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@xxxxxxxxx> Link: https://bugs.debian.org/1013299 Signed-off-by: Diederik de Haas <didi.debian@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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;
