pkt_sched: sch_drr: Fix oops in drr_change_class.

drr_change_class lacks a check for NULL of tca[TCA_OPTIONS], so oops
is possible.

Reported-by: Denys Fedoryschenko <denys@visp.net.lb>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c
index f6b4fa97df70..e36e94ab4e10 100644
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -66,11 +66,15 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 {
         struct drr_sched *q = qdisc_priv(sch);
         struct drr_class *cl = (struct drr_class *)*arg;
+        struct nlattr *opt = tca[TCA_OPTIONS];
         struct nlattr *tb[TCA_DRR_MAX + 1];
         u32 quantum;
         int err;
 
-        err = nla_parse_nested(tb, TCA_DRR_MAX, tca[TCA_OPTIONS], drr_policy);
+        if (!opt)
+                return -EINVAL;
+
+        err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy);
         if (err < 0)
                 return err;