path: root/net/sched/sch_api.c
diff options
authorCong Wang <xiyou.wangcong@gmail.com>2017-10-27 22:08:56 -0700
committerDavid S. Miller <davem@davemloft.net>2017-10-29 17:55:03 +0900
commit50317fce2cc70a2bbbc4b42c31bbad510382a53c (patch)
treef95a808773161eb27382e2be0ae9b7877871d7a8 /net/sched/sch_api.c
parentd04adf1b355181e737b6b1e23d801b07f0b7c4c0 (diff)
net_sched: avoid matching qdisc with zero handle
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 <dcaratti@redhat.com> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Eric Dumazet <edumazet@google.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/sch_api.c')
1 files changed, 2 insertions, 0 deletions
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index c6deb74e3d2f..22bc6fc48311 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -301,6 +301,8 @@ struct Qdisc *qdisc_lookup(struct net_device *dev, u32 handle)
struct Qdisc *q;
+ if (!handle)
+ return NULL;
q = qdisc_match_from_root(dev->qdisc, handle);
if (q)
goto out;