Re: [PATCH v4 RESEND] drm/client: fix null pointer dereference in drm_client_modeset_probe

[Thomas Zimmermann <tzimmermann@suse.de>]

Am 02.08.24 um 06:47 schrieb Ma Ke:
> In drm_client_modeset_probe(), the return value of drm_mode_duplicate() is
> assigned to modeset->mode, which will lead to a possible NULL pointer
> dereference on failure of drm_mode_duplicate(). Add a check to avoid npd.
>
> Cc: stable@vger.kernel.org
> Fixes: cf13909aee05 ("drm/fb-helper: Move out modeset config code")
> Signed-off-by: Ma Ke <make24@iscas.ac.cn>

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>

> ---
> Changes in v4:
> - modified patch, set ret and break to handle error rightly.
> Changes in v3:
> - modified patch as suggestions, returned error directly when failing to
> get modeset->mode.
> Changes in v2:
> - added the recipient's email address, due to the prolonged absence of a
> response from the recipients.
> - added Cc stable.
> ---
>   drivers/gpu/drm/drm_client_modeset.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
> index 31af5cf37a09..cee5eafbfb81 100644
> --- a/drivers/gpu/drm/drm_client_modeset.c
> +++ b/drivers/gpu/drm/drm_client_modeset.c
> @@ -880,6 +880,11 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width,
>   
>   			kfree(modeset->mode);
>   			modeset->mode = drm_mode_duplicate(dev, mode);
> +			if (!modeset->mode) {
> +				ret = -ENOMEM;
> +				break;
> +			}
> +
>   			drm_connector_get(connector);
>   			modeset->connectors[modeset->num_connectors++] = connector;
>   			modeset->x = offset->x;

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)