devlink: fix netns refcount leak in devlink_nl_cmd_reload()

stable inclusion
from stable-v5.10.85
commit 4b7e90672af8e0c78205db006f1b0a20ebd07f5f
bugzilla: 186032 https://gitee.com/openeuler/kernel/issues/I4QVI4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4b7e90672af8e0c78205db006f1b0a20ebd07f5f

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

commit 4dbb0dad upstream.

While preparing my patch series adding netns refcount tracking,
I spotted bugs in devlink_nl_cmd_reload()

Some error paths forgot to release a refcount on a netns.

To fix this, we can reduce the scope of get_net()/put_net()
section around the call to devlink_reload().

Fixes: ccdf0721 ("devlink: Add reload action option to devlink reload command")
Fixes: dc64cc7c ("devlink: Add devlink reload limit option")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Moshe Shemesh <moshe@mellanox.com>
Cc: Jacob Keller <jacob.e.keller@intel.com>
Cc: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: NLeon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20211205192822.1741045-1-eric.dumazet@gmail.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/core/devlink.c

@@ -3265,14 +3265,6 @@ static int devlink_nl_cmd_reload(struct sk_buff *skb, struct genl_info *info)
 		return err;
 	}
 
-	if (info->attrs[DEVLINK_ATTR_NETNS_PID] ||
-	    info->attrs[DEVLINK_ATTR_NETNS_FD] ||
-	    info->attrs[DEVLINK_ATTR_NETNS_ID]) {
-		dest_net = devlink_netns_get(skb, info);
-		if (IS_ERR(dest_net))
-			return PTR_ERR(dest_net);
-	}
-
 	if (info->attrs[DEVLINK_ATTR_RELOAD_ACTION])
 		action = nla_get_u8(info->attrs[DEVLINK_ATTR_RELOAD_ACTION]);
 	else
@@ -3315,6 +3307,14 @@ static int devlink_nl_cmd_reload(struct sk_buff *skb, struct genl_info *info)
 			return -EINVAL;
 		}
 	}
+	if (info->attrs[DEVLINK_ATTR_NETNS_PID] ||
+	    info->attrs[DEVLINK_ATTR_NETNS_FD] ||
+	    info->attrs[DEVLINK_ATTR_NETNS_ID]) {
+		dest_net = devlink_netns_get(skb, info);
+		if (IS_ERR(dest_net))
+			return PTR_ERR(dest_net);
+	}
+
 	err = devlink_reload(devlink, dest_net, action, limit, &actions_performed, info->extack);
 
 	if (dest_net)