From c485792ed6491865037abc1e18bbd66240112c93 Mon Sep 17 00:00:00 2001 From: Gao Feng Date: Wed, 28 Jun 2017 12:53:54 +0800 Subject: net: sched: Fix one possible panic when no destroy callback commit c1a4872ebfb83b1af7144f7b29ac8c4b344a12a8 upstream. When qdisc fail to init, qdisc_create would invoke the destroy callback to cleanup. But there is no check if the callback exists really. So it would cause the panic if there is no real destroy callback like the qdisc codel, fq, and so on. Take codel as an example following: When a malicious user constructs one invalid netlink msg, it would cause codel_init->codel_change->nla_parse_nested failed. Then kernel would invoke the destroy callback directly but qdisc codel doesn't define one. It causes one panic as a result. Now add one the check for destroy to avoid the possible panic. Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation") Signed-off-by: Gao Feng Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_api.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/sched') diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c index 35ed0d8c53b0..6d340cd6e2a7 100644 --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -1005,7 +1005,8 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue, return sch; } /* ops->init() failed, we call ->destroy() like qdisc_create_dflt() */ - ops->destroy(sch); + if (ops->destroy) + ops->destroy(sch); err_out3: dev_put(dev); kfree((char *) sch - sch->padded); -- cgit v1.2.3