6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Duoming Zhou duoming@zju.edu.cn
[ 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: d01ffb9eee4a ("ax25: add refcount in ax25_dev to avoid UAF bugs") Suggested-by: Dan Carpenter dan.carpenter@linaro.org Signed-off-by: Duoming Zhou duoming@zju.edu.cn Reviewed-by: Dan Carpenter dan.carpenter@linaro.org Link: https://lore.kernel.org/r/7ce3b23a40d9084657ba1125432f0ecc380cbc80.171524701... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ax25/ax25_dev.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c index 52ccc37d5687a..c9d55b99a7a57 100644 --- a/net/ax25/ax25_dev.c +++ b/net/ax25/ax25_dev.c @@ -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);