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| author | Cong Wang <xiyou.wangcong@gmail.com> | 2017-10-27 22:08:56 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-10-29 17:55:03 +0900 |
| commit | 50317fce2cc70a2bbbc4b42c31bbad510382a53c (patch) | |
| tree | f95a808773161eb27382e2be0ae9b7877871d7a8 | |
| parent | d04adf1b355181e737b6b1e23d801b07f0b7c4c0 (diff) | |
| download | lwn-50317fce2cc70a2bbbc4b42c31bbad510382a53c.tar.gz lwn-50317fce2cc70a2bbbc4b42c31bbad510382a53c.zip | |
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>
| -rw-r--r-- | net/sched/sch_api.c | 2 |
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; |