net/hsr: Fix NULL pointer dereference on incomplete hsr_newlink() params.

If none of the slave interfaces are specified, struct nlattr *data[] may
be NULL. Make sure to check for that.

While I'm at it, fix the horrible error messages displayed when only one
of the slave interfaces isn't specified.

Signed-off-by: Arvid Brodin <arvid.brodin@alten.se>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 2 deletions

diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c
index fbdf53f1d874..a2c7e4c0ac1e 100644
--- a/net/hsr/hsr_netlink.c
+++ b/net/hsr/hsr_netlink.c
@@ -37,13 +37,17 @@ static int hsr_newlink(struct net *src_net, struct net_device *dev,
         struct net_device *link[2];
         unsigned char multicast_spec;
 
+        if (!data) {
+                netdev_info(dev, "HSR: No slave devices specified\n");
+                return -EINVAL;
+        }
         if (!data[IFLA_HSR_SLAVE1]) {
-                netdev_info(dev, "IFLA_HSR_SLAVE1 missing!\n");
+                netdev_info(dev, "HSR: Slave1 device not specified\n");
                 return -EINVAL;
         }
         link[0] = __dev_get_by_index(src_net, nla_get_u32(data[IFLA_HSR_SLAVE1]));
         if (!data[IFLA_HSR_SLAVE2]) {
-                netdev_info(dev, "IFLA_HSR_SLAVE2 missing!\n");
+                netdev_info(dev, "HSR: Slave2 device not specified\n");
                 return -EINVAL;
         }
         link[1] = __dev_get_by_index(src_net, nla_get_u32(data[IFLA_HSR_SLAVE2]));