[PATCH net-next 4/7] dcb: validate netlink attribute link

[Stephen Hemminger <stephen@networkplumber.org>]

The dcb netlink code was not validating that the IEEE_APP netlink
element was correctly formed.  Initially discovered because of the
warning ‘dcbnl_ieee_app’ defined but not used.
This indicated that the message was not being fully validated.

Compile tested only. Do not have DCB setup.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
---
 net/dcb/dcbnl.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/dcb/dcbnl.c b/net/dcb/dcbnl.c
index 3202d75329b5..52f0f2fc0a51 100644
--- a/net/dcb/dcbnl.c
+++ b/net/dcb/dcbnl.c
@@ -178,10 +178,6 @@ static const struct nla_policy dcbnl_ieee_policy[DCB_ATTR_IEEE_MAX + 1] = {
 	[DCB_ATTR_IEEE_QCN_STATS]   = {.len = sizeof(struct ieee_qcn_stats)},
 };
 
-static const struct nla_policy dcbnl_ieee_app[DCB_ATTR_IEEE_APP_MAX + 1] = {
-	[DCB_ATTR_IEEE_APP]	    = {.len = sizeof(struct dcb_app)},
-};
-
 /* DCB number of traffic classes nested attributes. */
 static const struct nla_policy dcbnl_featcfg_nest[DCB_FEATCFG_ATTR_MAX + 1] = {
 	[DCB_FEATCFG_ATTR_ALL]      = {.type = NLA_FLAG},
@@ -1466,8 +1462,15 @@ static int dcbnl_ieee_set(struct net_device *netdev, struct nlmsghdr *nlh,
 
 		nla_for_each_nested(attr, ieee[DCB_ATTR_IEEE_APP_TABLE], rem) {
 			struct dcb_app *app_data;
+
 			if (nla_type(attr) != DCB_ATTR_IEEE_APP)
 				continue;
+
+			if (nla_len(attr) != sizeof(struct dcb_app)) {
+				err = -ERANGE;
+				goto err;
+			}
+
 			app_data = nla_data(attr);
 			if (ops->ieee_setapp)
 				err = ops->ieee_setapp(netdev, app_data);
-- 
2.11.0