[PATCH 3.2 181/199] drop_monitor: add missing call to genlmsg_end

[Ben Hutchings]

3.2.87-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Reiter Wolfgang <wr0112...@gmail.com>

[ Upstream commit 4200462d88f47f3759bdf4705f87e207b0f5b2e4 ]

Update nlmsg_len field with genlmsg_end to enable userspace processing
using nlmsg_next helper. Also adds error handling.

Signed-off-by: Reiter Wolfgang <wr0112...@gmail.com>
Acked-by: Neil Horman <nhor...@tuxdriver.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 net/core/drop_monitor.c | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -77,6 +77,7 @@ static struct sk_buff *reset_per_cpu_dat
        struct nlattr *nla;
        struct sk_buff *skb;
        unsigned long flags;
+       void *msg_header;
 
        al = sizeof(struct net_dm_alert_msg);
        al += dm_hit_limit * sizeof(struct net_dm_drop_point);
@@ -84,17 +85,31 @@ static struct sk_buff *reset_per_cpu_dat
 
        skb = genlmsg_new(al, GFP_KERNEL);
 
-       if (skb) {
-               genlmsg_put(skb, 0, 0, &net_drop_monitor_family,
-                               0, NET_DM_CMD_ALERT);
-               nla = nla_reserve(skb, NLA_UNSPEC,
-                                 sizeof(struct net_dm_alert_msg));
-               msg = nla_data(nla);
-               memset(msg, 0, al);
-       } else {
-               mod_timer(&data->send_timer, jiffies + HZ / 10);
+       if (!skb)
+               goto err;
+
+       msg_header = genlmsg_put(skb, 0, 0, &net_drop_monitor_family,
+                                0, NET_DM_CMD_ALERT);
+       if (!msg_header) {
+               nlmsg_free(skb);
+               skb = NULL;
+               goto err;
+       }
+       nla = nla_reserve(skb, NLA_UNSPEC,
+                         sizeof(struct net_dm_alert_msg));
+       if (!nla) {
+               nlmsg_free(skb);
+               skb = NULL;
+               goto err;
        }
+       msg = nla_data(nla);
+       memset(msg, 0, al);
+       genlmsg_end(skb, msg_header);
+       goto out;
 
+err:
+       mod_timer(&data->send_timer, jiffies + HZ / 10);
+out:
        spin_lock_irqsave(&data->lock, flags);
        swap(data->skb, skb);
        spin_unlock_irqrestore(&data->lock, flags);