[Intel-gfx] [PATCH] drm/i915: Limit the for_each_set_bit() to the valid range

[Ville Syrjälä]

On Wed, Jan 16, 2019 at 03:54:21PM +0000, Chris Wilson wrote:
> Let static analyzers (smatch) know that we are not going to wander off
> the end of the array by providing a tight upper bound:
> 
> drivers/gpu/drm/i915/intel_display.c:9532 hsw_get_transcoder_state() error: buffer overflow 'dev_priv->__info.trans_offsets' 6 <= 31
> 
> References: 0716931a82b4 ("drm/i915/icl: fix transcoder state readout")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Jani Nikula <jani.nikula at intel.com>
> Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
> Cc: Imre Deak <imre.deak at intel.com>
> Cc: Madhav Chauhan <madhav.chauhan at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 62d61fcad89c..b087ed285cc1 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -9526,7 +9526,9 @@ static bool hsw_get_transcoder_state(struct intel_crtc *crtc,
>  	 * XXX: Do intel_display_power_get_if_enabled before reading this (for
>  	 * consistency and less surprising code; it's in always on power).
>  	 */
> -	for_each_set_bit(panel_transcoder, &panel_transcoder_mask, 32) {
> +	for_each_set_bit(panel_transcoder,
> +			 &panel_transcoder_mask,
> +			 ARRAY_SIZE(INTEL_INFO(dev_priv)->trans_offsets)) {

Or just I915_MAX_TRANSCODERS maybe? Doesn't really matter I suppose.

Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

>  		enum pipe trans_pipe;
>  
>  		tmp = I915_READ(TRANS_DDI_FUNC_CTL(panel_transcoder));
> -- 
> 2.20.1

-- 
Ville Syrjälä
Intel