drop_monitor: add missing call to genlmsg_end

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

Signed-off-by: Reiter Wolfgang <wr0112358@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 24 insertions, 9 deletions

diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 8e0c0635ee97..f465bad2ef2c 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -75,6 +75,7 @@ static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data)
         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);
@@ -82,17 +83,31 @@ static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data)
 
         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);