[PATCH 6.18 043/122] gpio: virtuser: fix UAF in configfs release path

Greg Kroah-Hartman
2026-02-04T15:30:20Z

From: Yuhao Huang <nekowong743@gmail.com>

[ Upstream commit 53ad4a948a4586359b841d607c08fb16c5503230 ]

The gpio-virtuser configfs release path uses guard(mutex) to protect
the device structure. However, the device is freed before the guard
cleanup runs, causing mutex_unlock() to operate on freed memory.

Specifically, gpio_virtuser_device_config_group_release() destroys
the mutex and frees the device while still inside the guard(mutex)
scope. When the function returns, the guard cleanup invokes
mutex_unlock(&dev->lock), resulting in a slab use-after-free.

Limit the mutex lifetime by using a scoped_guard() only around the
activation check, so that the lock is released before mutex_destroy()
and kfree() are called.

Fixes: 91581c4b3f29 ("gpio: virtuser: new virtual testing driver for the GPIO API")
Signed-off-by: Yuhao Huang <nekowong743@gmail.com>
Link: https://lore.kernel.org/r/20260126040348.11167-1-yuhaohuang@YuhaodeMacBook-Pro.local
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpio/gpio-virtuser.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-virtuser.c b/drivers/gpio/gpio-virtuser.c
index a10eab7d2617e..252fec5ea3835 100644
--- a/drivers/gpio/gpio-virtuser.c
+++ b/drivers/gpio/gpio-virtuser.c
@@ -1684,10 +1684,10 @@ static void gpio_virtuser_device_config_group_release(struct config_item *item)
{
struct gpio_virtuser_device *dev = to_gpio_virtuser_device(item);

- guard(mutex)(&dev->lock);
-
- if (gpio_virtuser_device_is_live(dev))
- gpio_virtuser_device_deactivate(dev);
+ scoped_guard(mutex, &dev->lock) {
+ if (gpio_virtuser_device_is_live(dev))
+ gpio_virtuser_device_deactivate(dev);
+ }

mutex_destroy(&dev->lock);
ida_free(&gpio_virtuser_ida, dev->id);
--
2.51.0