Commit c2968f7b authored by Duoming Zhou's avatar Duoming Zhou Committed by Zhengchao Shao
Browse files

ax25: Fix reference count leak issue of net_device 

stable inclusion
from stable-v6.6.33
commit 965d940fb7414b310a22666503d2af69459c981b
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA6SG4
CVE: CVE-2024-38554

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=965d940fb7414b310a22666503d2af69459c981b



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

[ Upstream commit 36e56b1b002bb26440403053f19f9e1a8bc075b2 ]

There is a reference count leak issue of the object "net_device" in
ax25_dev_device_down(). When the ax25 device is shutting down, the
ax25_dev_device_down() drops the reference count of net_device one
or zero times depending on if we goto unlock_put or not, which will
cause memory leak.

In order to solve the above issue, decrease the reference count of
net_device after dev->ax25_ptr is set to null.

Fixes: d01ffb9e ("ax25: add refcount in ax25_dev to avoid UAF bugs")
Suggested-by: default avatarDan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: default avatarDuoming Zhou <duoming@zju.edu.cn>
Reviewed-by: default avatarDan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/7ce3b23a40d9084657ba1125432f0ecc380cbc80.1715247018.git.duoming@zju.edu.cn


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarZhengchao Shao <shaozhengchao@huawei.com>
parent 3b421b60

net/ax25/ax25_dev.c

+1 −6
Original line number Diff line number Diff line
@@ -118,15 +118,10 @@ void ax25_dev_device_down(struct net_device *dev) 
	list_for_each_entry(s, &ax25_dev_list, list) {

		if (s == ax25_dev) {

			list_del(&s->list);

			goto unlock_put;

			break;

		}

	}

	dev->ax25_ptr = NULL;

	spin_unlock_bh(&ax25_dev_lock);

	ax25_dev_put(ax25_dev);

	return;



unlock_put:

	dev->ax25_ptr = NULL;

	spin_unlock_bh(&ax25_dev_lock);

	netdev_put(dev, &ax25_dev->dev_tracker);