[PATCH 01/12] drm/client: Fully protect modes[] with dev->mode_config.mutex

[Dmitry Baryshkov]

On Thu, Apr 04, 2024 at 11:33:25PM +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> The modes[] array contains pointers to modes on the connectors'
> mode lists, which are protected by dev->mode_config.mutex.
> Thus we need to extend modes[] the same protection or by the
> time we use it the elements may already be pointing to
> freed/reused memory.
> 
> Cc: stable at vger.kernel.org
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/10583
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>

I tried looking for the proper Fixes tag, but it looks like it might be
something like 386516744ba4 ("drm/fb: fix fbdev object model + cleanup properly.")


> ---
>  drivers/gpu/drm/drm_client_modeset.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
> index 871e4e2129d6..0683a129b362 100644
> --- a/drivers/gpu/drm/drm_client_modeset.c
> +++ b/drivers/gpu/drm/drm_client_modeset.c
> @@ -777,6 +777,7 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width,
>  	unsigned int total_modes_count = 0;
>  	struct drm_client_offset *offsets;
>  	unsigned int connector_count = 0;
> +	/* points to modes protected by mode_config.mutex */
>  	struct drm_display_mode **modes;
>  	struct drm_crtc **crtcs;
>  	int i, ret = 0;
> @@ -845,7 +846,6 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width,
>  		drm_client_pick_crtcs(client, connectors, connector_count,
>  				      crtcs, modes, 0, width, height);
>  	}
> -	mutex_unlock(&dev->mode_config.mutex);
>  
>  	drm_client_modeset_release(client);
>  
> @@ -875,6 +875,7 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width,
>  			modeset->y = offset->y;
>  		}
>  	}
> +	mutex_unlock(&dev->mode_config.mutex);
>  
>  	mutex_unlock(&client->modeset_mutex);
>  out:
> -- 
> 2.43.2
> 

-- 
With best wishes
Dmitry