2024-04-07 06:31:12

by Huai-Yuan Liu

Subject: [PATCH V2] drm/arm/malidp: fix a possible null pointer dereference

In malidp_mw_connector_reset, new memory is allocated with kzalloc, but
no check is performed. In order to prevent null pointer dereferencing,
ensure that mw_state is checked before calling
__drm_atomic_helper_connector_reset.

Fixes: 8cbc5caf36ef ("drm: mali-dp: Add writeback connector")
Signed-off-by: Huai-Yuan Liu <[email protected]>
---
V2:
* In patch V2, we additionally set connector->state to NULL. In this way
we can ensure that there is no state pointing to freed memory.
Thanks to Liviu Dudau for helpful suggestion.
---
drivers/gpu/drm/arm/malidp_mw.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/arm/malidp_mw.c b/drivers/gpu/drm/arm/malidp_mw.c
index 626709bec6f5..2577f0cef8fc 100644
--- a/drivers/gpu/drm/arm/malidp_mw.c
+++ b/drivers/gpu/drm/arm/malidp_mw.c
@@ -72,7 +72,10 @@ static void malidp_mw_connector_reset(struct drm_connector *connector)
__drm_atomic_helper_connector_destroy_state(connector->state);

kfree(connector->state);
- __drm_atomic_helper_connector_reset(connector, &mw_state->base);
+ connector->state = NULL;
+
+ if (mw_state)
+ __drm_atomic_helper_connector_reset(connector, &mw_state->base);
}

static enum drm_connector_status
--
2.34.1

2024-04-08 10:16:09

by Liviu Dudau

Subject: Re: [PATCH V2] drm/arm/malidp: fix a possible null pointer dereference

On Sun, Apr 07, 2024 at 02:30:53PM +0800, Huai-Yuan Liu wrote:
> In malidp_mw_connector_reset, new memory is allocated with kzalloc, but
> no check is performed. In order to prevent null pointer dereferencing,
> ensure that mw_state is checked before calling
> __drm_atomic_helper_connector_reset.
>
> Fixes: 8cbc5caf36ef ("drm: mali-dp: Add writeback connector")
> Signed-off-by: Huai-Yuan Liu <[email protected]>

Reviewed-by: Liviu Dudau <[email protected]>

Thanks for the patch. I will pull it into drm-misc-fixes before the end of the week.

Best regards,
Liviu

> ---
> V2:
> * In patch V2, we additionally set connector->state to NULL. In this way
> we can ensure that there is no state pointing to freed memory.
> Thanks to Liviu Dudau for helpful suggestion.
> ---
> drivers/gpu/drm/arm/malidp_mw.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/arm/malidp_mw.c b/drivers/gpu/drm/arm/malidp_mw.c
> index 626709bec6f5..2577f0cef8fc 100644
> --- a/drivers/gpu/drm/arm/malidp_mw.c
> +++ b/drivers/gpu/drm/arm/malidp_mw.c
> @@ -72,7 +72,10 @@ static void malidp_mw_connector_reset(struct drm_connector *connector)
> __drm_atomic_helper_connector_destroy_state(connector->state);
>
> kfree(connector->state);
> - __drm_atomic_helper_connector_reset(connector, &mw_state->base);
> + connector->state = NULL;
> +
> + if (mw_state)
> + __drm_atomic_helper_connector_reset(connector, &mw_state->base);
> }
>
> static enum drm_connector_status
> --
> 2.34.1
>

--
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