Subject: [PATCH AUTOSEL 4.14 06/39] batman-adv: Fix refcnt leak in batadv_store_throughput_override

From: Sasha Levin <[email-masked]>
Date: Thu, 14 May 2020 14:54:23 -0400

From: Xiyu Yang <[email-masked]>

[ Upstream commit 6107c5da0fca8b50b4d3215e94d619d38cc4a18c ]

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: 0b5ecc6811bd ("batman-adv: add throughput override attribute to hard_ifaces")
Signed-off-by: Xiyu Yang <[email-masked]>
Signed-off-by: Xin Tan <[email-masked]>
Signed-off-by: Sven Eckelmann <[email-masked]>
Signed-off-by: Simon Wunderlich <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 net/batman-adv/sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c
index e44a7f29d598e..ed789845d195c 100644
--- a/net/batman-adv/sysfs.c
+++ b/net/batman-adv/sysfs.c
@@ -1081,7 +1081,7 @@ static ssize_t batadv_store_throughput_override(struct kobject *kobj,
 	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)
-- 
2.20.1