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>

2 files changed, 26 insertions, 19 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;
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 0bbce229ac69..d7468baf890e 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -977,7 +977,7 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n)
         struct tcmsg *tcm = nlmsg_data(n);
         struct nlattr *tca[TCA_MAX + 1];
         struct net_device *dev;
-        u32 clid = tcm->tcm_parent;
+        u32 clid;
         struct Qdisc *q = NULL;
         struct Qdisc *p = NULL;
         int err;
@@ -985,14 +985,15 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n)
         if ((n->nlmsg_type != RTM_GETQDISC) && !capable(CAP_NET_ADMIN))
                 return -EPERM;
 
-        dev = __dev_get_by_index(net, tcm->tcm_ifindex);
-        if (!dev)
-                return -ENODEV;
-
         err = nlmsg_parse(n, sizeof(*tcm), tca, TCA_MAX, NULL);
         if (err < 0)
                 return err;
 
+        dev = __dev_get_by_index(net, tcm->tcm_ifindex);
+        if (!dev)
+                return -ENODEV;
+
+        clid = tcm->tcm_parent;
         if (clid) {
                 if (clid != TC_H_ROOT) {
                         if (TC_H_MAJ(clid) != TC_H_MAJ(TC_H_INGRESS)) {
@@ -1053,6 +1054,10 @@ static int tc_modify_qdisc(struct sk_buff *skb, struct nlmsghdr *n)
 
 replay:
         /* Reinit, just in case something touches this. */
+        err = nlmsg_parse(n, sizeof(*tcm), tca, TCA_MAX, NULL);
+        if (err < 0)
+                return err;
+
         tcm = nlmsg_data(n);
         clid = tcm->tcm_parent;
         q = p = NULL;
@@ -1061,9 +1066,6 @@ replay:
         if (!dev)
                 return -ENODEV;
 
-        err = nlmsg_parse(n, sizeof(*tcm), tca, TCA_MAX, NULL);
-        if (err < 0)
-                return err;
 
         if (clid) {
                 if (clid != TC_H_ROOT) {
@@ -1382,22 +1384,22 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n)
         const struct Qdisc_class_ops *cops;
         unsigned long cl = 0;
         unsigned long new_cl;
-        u32 portid = tcm->tcm_parent;
-        u32 clid = tcm->tcm_handle;
-        u32 qid = TC_H_MAJ(clid);
+        u32 portid;
+        u32 clid;
+        u32 qid;
         int err;
 
         if ((n->nlmsg_type != RTM_GETTCLASS) && !capable(CAP_NET_ADMIN))
                 return -EPERM;
 
-        dev = __dev_get_by_index(net, tcm->tcm_ifindex);
-        if (!dev)
-                return -ENODEV;
-
         err = nlmsg_parse(n, sizeof(*tcm), tca, TCA_MAX, NULL);
         if (err < 0)
                 return err;
 
+        dev = __dev_get_by_index(net, tcm->tcm_ifindex);
+        if (!dev)
+                return -ENODEV;
+
         /*
            parent == TC_H_UNSPEC - unspecified parent.
            parent == TC_H_ROOT   - class is root, which has no parent.
@@ -1413,6 +1415,10 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n)
 
         /* Step 1. Determine qdisc handle X:0 */
 
+        portid = tcm->tcm_parent;
+        clid = tcm->tcm_handle;
+        qid = TC_H_MAJ(clid);
+
         if (portid != TC_H_ROOT) {
                 u32 qid1 = TC_H_MAJ(portid);