Re: [PATCH] drm/i915/vrr: require valid min/max vfreq for VRR

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Jun 25, 2026 at 04:10:40PM +0300, Jani Nikula wrote:
> Ensure the EDID provided min/max vfreq are valid. Most scenarios are
> already covered (by coincidence) through the checks in
> intel_vrr_is_capable() and intel_vrr_is_in_range(), but be more explicit
> about it. At worst, a zero min_vfreq could lead to a division by zero in
> intel_vrr_compute_vmax().
> 
> Discovered using AI-assisted static analysis confirmed by Intel Product
> Security.
> 
> Reported-by: Martin Hodo <martin.hodo@intel.com>
> Fixes: 117cd09ba528 ("drm/i915/display/dp: Compute VRR state in atomic_check")
> Cc: <stable@vger.kernel.org> # v5.12+
> Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_vrr.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
> index 5d9b11185296..bffbdee76ee1 100644
> --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> @@ -76,6 +76,10 @@ bool intel_vrr_is_capable(struct intel_connector *connector)
>  		return false;
>  	}
>  
> +	if (!info->monitor_range.min_vfreq || !info->monitor_range.max_vfreq ||
> +	    info->monitor_range.min_vfreq > info->monitor_range.max_vfreq)
> +		return false;

Perhaps it should be the responsibility of the EDID parser to make sure
the range isn't completely insane?

> +
>  	return info->monitor_range.max_vfreq - info->monitor_range.min_vfreq > 10;

I've been tempted to get rid of this completely arbitrary 10Hz thing as well.

>  }
>  
> -- 
> 2.47.3

-- 
Ville Syrjälä
Intel