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

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

[Qi Xi]

Add missing mutex unlock before returning from the error path in
cdns_mhdp_atomic_enable().

Fixes: 935a92a1c400 ("drm: bridge: cdns-mhdp8546: Fix possible null pointer dereference")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
---
 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 a614d1384f71..38726ae1bf15 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -1984,8 +1984,10 @@ 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);
 
-- 
2.33.0

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

[Luca Ceresoli]

Hello Qi Xi,

On Thu, 4 Sep 2025 11:44:47 +0800
Qi Xi <xiqi2@huawei.com> wrote:

> Add missing mutex unlock before returning from the error path in
> cdns_mhdp_atomic_enable().
> 
> Fixes: 935a92a1c400 ("drm: bridge: cdns-mhdp8546: Fix possible null pointer dereference")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Qi Xi <xiqi2@huawei.com>

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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

[Luca Ceresoli]

On Thu, 04 Sep 2025 11:44:47 +0800, Qi Xi wrote:
> Add missing mutex unlock before returning from the error path in
> cdns_mhdp_atomic_enable().
> 
> 

Applied, thanks!

[1/1] drm: bridge: cdns-mhdp8546: Fix missing mutex unlock on error path
      commit: 288dac9fb6084330d968459c750c838fd06e10e6

Best regards,
-- 
Luca Ceresoli <luca.ceresoli@bootlin.com>

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

[Aleksandr Mishin]

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 <amishin@t-argos.ru>
---
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

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

[Dmitry Baryshkov]

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 <amishin@t-argos.ru>
> ---
> 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 <dmitry.baryshkov@linaro.org>


-- 
With best wishes
Dmitry

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

[Markus Elfring]

…
> 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