netlink: have length check of rtnl msg before deref

When the legacy array rtm_min still exists, the length check within
these functions is covered by rtm_min[RTM_NEWTFILTER],
rtm_min[RTM_NEWQDISC] and rtm_min[RTM_NEWTCLASS].

But after Thomas Graf removed rtm_min several days ago, these checks
are missing. Other doit functions should be OK.

Signed-off-by: Hong Zhiguo <honkiko@gmail.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 4 deletions

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 9a04b981bc13..9d71d4ded53b 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -141,7 +141,12 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n)
 
         if ((n->nlmsg_type != RTM_GETTFILTER) && !capable(CAP_NET_ADMIN))
                 return -EPERM;
+
 replay:
+        err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL);
+        if (err < 0)
+                return err;
+
         t = nlmsg_data(n);
         protocol = TC_H_MIN(t->tcm_info);
         prio = TC_H_MAJ(t->tcm_info);
@@ -164,10 +169,6 @@ replay:
         if (dev == NULL)
                 return -ENODEV;
 
-        err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL);
-        if (err < 0)
-                return err;
-
         /* Find qdisc */
         if (!parent) {
                 q = dev->qdisc;