In hantro_probe, vpu->watchdog_work is bound with
hantro_watchdog. Then hantro_end_prepare_run may
be called to start the work.
If we close the file or remove the module which will
call hantro_release and hantro_remove to make cleanup,
there may be an unfinished work. The possible sequence
is as follows, which will cause a typical UAF bug.
The same thing will happen in hantro_release, and use
ctx after freeing it.
Fix it by canceling the work before cleanup in hantro_release.
CPU0 CPU1
|hantro_watchdog
hantro_remove |
v4l2_m2m_release |
kfree(m2m_dev); |
|
| v4l2_m2m_get_curr_priv
| m2m_dev->curr_ctx //use
Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx>
---
v3:
- use cancel_delayed_work_sync instead of cancel_delayed_work and add it to
hantro_release suggested by Hans Verkuil
v2:
- move the cancel-work-related code to hantro_remove suggested by Hans Verkuil
---
drivers/media/platform/verisilicon/hantro_drv.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/media/platform/verisilicon/hantro_drv.c b/drivers/media/platform/verisilicon/hantro_drv.c
index b0aeedae7b65..86a4c0fa8c7d 100644
--- a/drivers/media/platform/verisilicon/hantro_drv.c
+++ b/drivers/media/platform/verisilicon/hantro_drv.c
@@ -597,6 +597,7 @@ static int hantro_release(struct file *filp)
struct hantro_ctx *ctx =
container_of(filp->private_data, struct hantro_ctx, fh);
+ cancel_delayed_work_sync(&ctx->dev->watchdog_work);
/*
* No need for extra locking because this was the last reference
* to this file.
@@ -1099,6 +1100,7 @@ static int hantro_remove(struct platform_device *pdev)
v4l2_info(&vpu->v4l2_dev, "Removing %s\n", pdev->name);
+ cancel_delayed_work_sync(&vpu->watchdog_work);
media_device_unregister(&vpu->mdev);
hantro_remove_dec_func(vpu);
hantro_remove_enc_func(vpu);
--
2.25.1
