4.13-stable review patch. If anyone has any objections, please let me know.
------------------ From: Cong Wang <[email protected]> [ Upstream commit 50317fce2cc70a2bbbc4b42c31bbad510382a53c ] Davide found the following script triggers a NULL pointer dereference: ip l a name eth0 type dummy tc q a dev eth0 parent :1 handle 1: htb This is because for a freshly created netdevice noop_qdisc is attached and when passing 'parent :1', kernel actually tries to match the major handle which is 0 and noop_qdisc has handle 0 so is matched by mistake. Commit 69012ae425d7 tries to fix a similar bug but still misses this case. Handle 0 is not a valid one, should be just skipped. In fact, kernel uses it as TC_H_UNSPEC. Fixes: 69012ae425d7 ("net: sched: fix handling of singleton qdiscs with qdisc_hash") Fixes: 59cc1f61f09c ("net: sched:convert qdisc linked list to hashtable") Reported-by: Davide Caratti <[email protected]> Cc: Jiri Kosina <[email protected]> Cc: Eric Dumazet <[email protected]> Cc: Jamal Hadi Salim <[email protected]> Signed-off-by: Cong Wang <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/sched/sch_api.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -307,6 +307,8 @@ struct Qdisc *qdisc_lookup(struct net_de { struct Qdisc *q; + if (!handle) + return NULL; q = qdisc_match_from_root(dev->qdisc, handle); if (q) goto out;
