[PATCH v3] media: venus: fix use after free bug in venus_remove due to race condition

[Dikshita Agarwal]

From: Zheng Wang <zyytlz.wz@xxxxxxx>

in venus_probe, core->work is bound with venus_sys_error_handler, which is
used to handle error. The code use core->sys_err_done to make sync work.
The core->work is started in venus_event_notify.

If we call venus_remove, there might be an unfished work. The possible
sequence is as follows:

CPU0                  CPU1

                     |venus_sys_error_handler
venus_remove         |
hfi_destroy	 		 |
venus_hfi_destroy	 |
kfree(hdev);	     |
                     |hfi_reinit
					 |venus_hfi_queues_reinit
                     |//use hdev

Fix it by canceling the work in venus_remove.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: af2c3834c8ca ("[media] media: venus: adding core part and helper functions")
Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx>
Signed-off-by: Dikshita Agarwal <quic_dikshita@xxxxxxxxxxx>
---
Changes since v2:
- used cancel_delayed_work_sync instead of cancel_delayed_work

 drivers/media/platform/qcom/venus/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/media/platform/qcom/venus/core.c b/drivers/media/platform/qcom/venus/core.c
index a712dd4..c139270 100644
--- a/drivers/media/platform/qcom/venus/core.c
+++ b/drivers/media/platform/qcom/venus/core.c
@@ -424,6 +424,7 @@ static void venus_remove(struct platform_device *pdev)
 	struct device *dev = core->dev;
 	int ret;
 
+	cancel_delayed_work_sync(&core->work);
 	ret = pm_runtime_get_sync(dev);
 	WARN_ON(ret < 0);
 
-- 
2.7.4