[PATCH 4.9 19/59] drop_monitor: add missing call to genlmsg_end

From: Greg Kroah-Hartman
Date: Fri Jan 13 2017 - 07:02:33 EST


4.9-stable review patch. If anyone has any objections, please let me know.

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

From: Reiter Wolfgang <wr0112358@xxxxxxxxx>


[ 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 <wr0112358@xxxxxxxxx>
Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -80,6 +80,7 @@ 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);
@@ -87,17 +88,31 @@ 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);