From: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Date: Wed, 15 Apr 2020 16:31:50 +0800
Subject: batman-adv: Fix refcnt leak in batadv_show_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_show_throughput_override() returns, "hard_iface" becomes
invalid, so the refcount should be decreased to keep refcount balanced.

The issue happens in the normal path of
batadv_show_throughput_override(), which forgets to decrease the refcnt
increased by batadv_hardif_get_by_netdev() before the function returns,
causing a refcnt leak.

Fix this issue by calling batadv_hardif_put() before the
batadv_show_throughput_override() returns in the normal path.

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/f301bfed59b146a63471d0f147b767d7cafede6f

--- a/net/batman-adv/sysfs.c
+++ b/net/batman-adv/sysfs.c
@@ -1189,6 +1189,7 @@ static ssize_t batadv_show_throughput_ov
 
 	tp_override = atomic_read(&hard_iface->bat_v.throughput_override);
 
+	batadv_hardif_put(hard_iface);
 	return sprintf(buff, "%u.%u MBit\n", tp_override / 10,
 		       tp_override % 10);
 }