From: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Date: Wed, 15 Apr 2020 16:35:21 +0800
Subject: batman-adv: Fix refcnt leak in batadv_store_throughput_override

batadv_show_throughput_override() invokes batadv_hardif_get_by_netdev(),
which gets a batadv_hard_iface object from net_dev with increased refcnt
and its reference is assigned to a local pointer 'hard_iface'.

When batadv_store_throughput_override() returns, "hard_iface" becomes
invalid, so the refcount should be decreased to keep refcount balanced.

The issue happens in one error path of
batadv_store_throughput_override(). When batadv_parse_throughput()
returns NULL, the refcnt increased by batadv_hardif_get_by_netdev() is
not decreased, causing a refcnt leak.

Fix this issue by jumping to "out" label when batadv_parse_throughput()
returns NULL.

Fixes: c513176e4b7a ("batman-adv: add throughput override attribute to hard_ifaces")
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

Origin: upstream, https://git.open-mesh.org/batman-adv.git/commit/b69cd8bdbfd6fa7e61878c2fa9e6637406f40dd9

--- a/net/batman-adv/sysfs.c
+++ b/net/batman-adv/sysfs.c
@@ -1149,7 +1149,7 @@ static ssize_t batadv_store_throughput_o
 	ret = batadv_parse_throughput(net_dev, buff, "throughput_override",
 				      &tp_override);
 	if (!ret)
-		return count;
+		goto out;
 
 	old_tp_override = atomic_read(&hard_iface->bat_v.throughput_override);
 	if (old_tp_override == tp_override)