[PATCH v3] media: venus: fix use after free in vdec_close

[PATCH v3] media: venus: fix use after free in vdec_close

[Dikshita Agarwal]

There appears to be a possible use after free with vdec_close().
The firmware will add buffer release work to the work queue through
HFI callbacks as a normal part of decoding. Randomly closing the
decoder device from userspace during normal decoding can incur
a read after free for inst.

Fix it by cancelling the work in vdec_close.

Cc: stable@vger.kernel.org
Fixes: af2c3834c ("media: venus: adding core part and helper functions")
Signed-off-by: Dikshita Agarwal <quic_dikshita@quicinc.com>
---
Changes since v2:
- fixed email id

Changes since v1:
- Added fixes and stable tags

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

diff --git a/drivers/media/platform/qcom/venus/vdec.c b/drivers/media/platform/qcom/venus/vdec.c
index 29130a9..56f8a25 100644
--- a/drivers/media/platform/qcom/venus/vdec.c
+++ b/drivers/media/platform/qcom/venus/vdec.c
@@ -1747,6 +1747,7 @@ static int vdec_close(struct file *file)
 
 	vdec_pm_get(inst);
 
+	cancel_work_sync(&inst->delayed_process_work);
 	v4l2_m2m_ctx_release(inst->m2m_ctx);
 	v4l2_m2m_release(inst->m2m_dev);
 	vdec_ctrl_deinit(inst);
-- 
2.7.4

Re: [PATCH v3] media: venus: fix use after free in vdec_close

[Krzysztof Kozlowski]

On 06/05/2024 07:58, Dikshita Agarwal wrote:
> There appears to be a possible use after free with vdec_close().
> The firmware will add buffer release work to the work queue through
> HFI callbacks as a normal part of decoding. Randomly closing the
> decoder device from userspace during normal decoding can incur
> a read after free for inst.
> 
> Fix it by cancelling the work in vdec_close.
> 
> Cc: stable@vger.kernel.org
> Fixes: af2c3834c ("media: venus: adding core part and helper functions")

Please run scripts/checkpatch.pl and fix reported warnings. Then please
run `scripts/checkpatch.pl --strict` and (probably) fix more warnings.
Some warnings can be ignored, especially from --strict run, but the code
here looks like it needs a fix. Feel free to get in touch if the warning
is not clear.

This is written in your instruction - go/upstream - so be sure you
always follow it fully.


Best regards,
Krzysztof