linux-kernel - Re: [PATCH] drm/gma500: fix null pointer dereference in psb_intel_lvds_get

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Message-ID: <8734p0domn.fsf@intel.com>
Date: Wed, 26 Jun 2024 12:44:48 +0300
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: Ma Ke <make24@...as.ac.cn>, patrik.r.jakobsson@...il.com,
 maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
 tzimmermann@...e.de, airlied@...il.com, daniel@...ll.ch
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, Ma Ke
 <make24@...as.ac.cn>
Subject: Re: [PATCH] drm/gma500: fix null pointer dereference in
 psb_intel_lvds_get_modes

On Wed, 26 Jun 2024, Ma Ke <make24@...as.ac.cn> wrote:
> In psb_intel_lvds_get_modes(), the return value of drm_mode_duplicate() is
> assigned to mode, which will lead to a possible NULL pointer dereference
> on failure of drm_mode_duplicate(). Add a check to avoid npd.
>
> Signed-off-by: Ma Ke <make24@...as.ac.cn>
> ---
>  drivers/gpu/drm/gma500/psb_intel_lvds.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/gma500/psb_intel_lvds.c b/drivers/gpu/drm/gma500/psb_intel_lvds.c
> index 8486de230ec9..aa5bf2a8a319 100644
> --- a/drivers/gpu/drm/gma500/psb_intel_lvds.c
> +++ b/drivers/gpu/drm/gma500/psb_intel_lvds.c
> @@ -504,6 +504,8 @@ static int psb_intel_lvds_get_modes(struct drm_connector *connector)
>  	if (mode_dev->panel_fixed_mode != NULL) {
>  		struct drm_display_mode *mode =
>  		    drm_mode_duplicate(dev, mode_dev->panel_fixed_mode);
> +		if (!mode)
> +			return -ENOMEM;

Do not return negative values from .get_modes().

BR,
Jani.

>  		drm_mode_probed_add(connector, mode);
>  		return 1;
>  	}

-- 
Jani Nikula, Intel