batman-adv: Fix refcnt leak in batadv_show_throughput_override

commit f872de8185acf1b48b954ba5bd8f9bc0a0d14016 upstream.

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: 0b5ecc6811bd ("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>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c
index 31d7e239a1fd622fc52c9d8d056f903131f79b91..d3fb5396f94733281ac1a36937b466ce59015b32 100644 (file)
--- a/net/batman-adv/sysfs.c
+++ b/net/batman-adv/sysfs.c
@@ -1120,6 +1120,7 @@ static ssize_t batadv_show_throughput_override(struct kobject *kobj,
 
        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);
 }