[PATCH AUTOSEL 6.2 18/37] memstick: r592: Fix UAF bug in r592_remove due to race condition

Sasha Levin
2023-05-01T03:10:17Z

From: Zheng Wang <zyytlz.wz@163.com>

[ Upstream commit 63264422785021704c39b38f65a78ab9e4a186d7 ]

In r592_probe, dev->detect_timer was bound with r592_detect_timer.
In r592_irq function, the timer function will be invoked by mod_timer.

If we remove the module which will call hantro_release to make cleanup,
there may be a unfinished work. The possible sequence is as follows,
which will cause a typical UAF bug.

Fix it by canceling the work before cleanup in r592_remove.

CPU0 CPU1

|r592_detect_timer
r592_remove |
memstick_free_host|
put_device; |
kfree(host); |
|
| queue_work
| &host->media_checker //use

Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Link: https://lore.kernel.org/r/20230307164338.1246287-1-zyytlz.wz@163.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/memstick/host/r592.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/memstick/host/r592.c b/drivers/memstick/host/r592.c
index 1d35d147552d4..42bfc46842b82 100644
--- a/drivers/memstick/host/r592.c
+++ b/drivers/memstick/host/r592.c
@@ -829,7 +829,7 @@ static void r592_remove(struct pci_dev *pdev)
/* Stop the processing thread.
That ensures that we won't take any more requests */
kthread_stop(dev->io_thread);
-
+ del_timer_sync(&dev->detect_timer);
r592_enable_device(dev, false);

while (!error && dev->req) {
--
2.39.2