[Devel] [PATCH RHEL7 COMMIT] ms/drop_monitor: add missing call to genlmsg_end

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-1160.66.1.vz7.188.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1160.66.1.vz7.188.6
------>
commit db13cd3466e02d46740ed39e43ef9ae868905554
Author: Reiter Wolfgang <wr0112358 at gmail.com>
Date:   Mon Jul 4 21:51:51 2022 +0300

    ms/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 at gmail.com>
    Acked-by: Neil Horman <nhorman at tuxdriver.com>
    Signed-off-by: David S. Miller <davem at davemloft.net>
    (cherry picked from commit 4200462d88f47f3759bdf4705f87e207b0f5b2e4)
    
    Signed-off-by: Alexander Mikhalitsyn <alexander.mikhalitsyn at virtuozzo.com>
    
    =================
    Patchset description:
    drop_monitor: Add packet alert mode
    
    Just port and adapt packet alert mode feature for RHEL7 kernel.
    
    https://jira.sw.ru/browse/PSBM-140937
    
    Ported-by: Alexander Mikhalitsyn <alexander.mikhalitsyn at virtuozzo.com>
---
 net/core/drop_monitor.c | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 2d3980de28b33..1f4aa6fed5fe6 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);