2024-04-19 11:41:35

by Aleksandr Mishin

Subject: [PATCH] drm: bridge: cdns-mhdp8546: Fix missing mutex unlock on error path

In cdns_mhdp_atomic_enable(), there is an error return on failure of
drm_mode_duplicate() which leads to the mutex remaining locked.
Add a mutex unlock call.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 935a92a1c400 ("drm: bridge: cdns-mhdp8546: Fix possible null pointer dereference")
Signed-off-by: Aleksandr Mishin <[email protected]>
---
This patch is against drm-misc-next branch of drm-misc repo.

drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 8a91ef0ae065..65a4bd09d9c6 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2059,8 +2059,10 @@ static void cdns_mhdp_atomic_enable(struct drm_bridge *bridge,
mhdp_state = to_cdns_mhdp_bridge_state(new_state);

mhdp_state->current_mode = drm_mode_duplicate(bridge->dev, mode);
- if (!mhdp_state->current_mode)
- return;
+ if (!mhdp_state->current_mode) {
+ ret = -EINVAL;
+ goto out;
+ }

drm_mode_set_name(mhdp_state->current_mode);

--
2.30.2

2024-04-19 15:03:09

by Dmitry Baryshkov

Subject: Re: [PATCH] drm: bridge: cdns-mhdp8546: Fix missing mutex unlock on error path

On Fri, Apr 19, 2024 at 02:36:37PM +0300, Aleksandr Mishin wrote:
> In cdns_mhdp_atomic_enable(), there is an error return on failure of
> drm_mode_duplicate() which leads to the mutex remaining locked.
> Add a mutex unlock call.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 935a92a1c400 ("drm: bridge: cdns-mhdp8546: Fix possible null pointer dereference")
> Signed-off-by: Aleksandr Mishin <[email protected]>
> ---
> This patch is against drm-misc-next branch of drm-misc repo.
>
> drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
>


Reviewed-by: Dmitry Baryshkov <[email protected]>


--
With best wishes
Dmitry

2024-04-19 19:48:50

by Markus Elfring

Subject: Re: [PATCH] drm: bridge: cdns-mhdp8546: Fix missing mutex unlock on error path

…
> Add a mutex unlock call.

How do you think about a wording variant like the following?

Extend the exception handling so that the missed mutex_unlock() call
will be performed finally.


Regards,
Markus