On 2022-02-18 05:03, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Add a variant of drm_mode_copy() that explicitly clears out
> the list head of the destination mode. Helpful to guarantee
> we don't have stack garbage left in there for on-stack modes.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx>
Harry
> ---
> drivers/gpu/drm/drm_modes.c | 17 +++++++++++++++++
> include/drm/drm_modes.h | 2 ++
> 2 files changed, 19 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
> index 96b13e36293c..40d4ce4a1da4 100644
> --- a/drivers/gpu/drm/drm_modes.c
> +++ b/drivers/gpu/drm/drm_modes.c
> @@ -892,6 +892,23 @@ void drm_mode_copy(struct drm_display_mode *dst, const struct drm_display_mode *
> }
> EXPORT_SYMBOL(drm_mode_copy);
>
> +/**
> + * drm_mode_init - initialize the mode from another mode
> + * @dst: mode to overwrite
> + * @src: mode to copy
> + *
> + * Copy an existing mode into another mode, zeroing the
> + * list head of the destination mode. Typically used
> + * to guarantee the list head is not left with stack
> + * garbage in on-stack modes.
> + */
> +void drm_mode_init(struct drm_display_mode *dst, const struct drm_display_mode *src)
> +{
> + memset(dst, 0, sizeof(*dst));
> + drm_mode_copy(dst, src);
> +}
> +EXPORT_SYMBOL(drm_mode_init);
> +
> /**
> * drm_mode_duplicate - allocate and duplicate an existing mode
> * @dev: drm_device to allocate the duplicated mode for
> diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
> index 29ba4adf0c53..e6e5a588fab1 100644
> --- a/include/drm/drm_modes.h
> +++ b/include/drm/drm_modes.h
> @@ -484,6 +484,8 @@ void drm_mode_set_crtcinfo(struct drm_display_mode *p,
> int adjust_flags);
> void drm_mode_copy(struct drm_display_mode *dst,
> const struct drm_display_mode *src);
> +void drm_mode_init(struct drm_display_mode *dst,
> + const struct drm_display_mode *src);
> struct drm_display_mode *drm_mode_duplicate(struct drm_device *dev,
> const struct drm_display_mode *mode);
> bool drm_mode_match(const struct drm_display_mode *mode1,
