Subject: [PATCH net-next 10/10] net/hsr: Fix NULL pointer dereference on incomplete hsr_newlink() params.

From: Arvid Brodin <[email-masked]>
Date: Fri, 4 Jul 2014 23:42:00 +0200

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 <[email-masked]>
---
 net/hsr/hsr_netlink.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c
index fbdf53f..a2c7e4c 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]));
-- 
1.8.3.2

-- 
Arvid Brodin | Consultant (Linux)
ALTEN | Knarrarnäsgatan 7 | SE-164 40 Kista | Sweden
[email-masked] | www.alten.se/en/