[Intel-gfx] [PATCH 1/2] drm/i915: Don't attempt to read an unitialized stack value

[Daniel Vetter]

On Fri, Jul 12, 2013 at 04:24:40PM +0100, Damien Lespiau wrote:
> If intel_sdvo_get_value() fails here, val is unitialized and the cross
> check will compare the pipe config multiplier with a bogus value.
> 
> Instead, only set encoder_pixel_multiplier when the sdvo command has
> been successful. The cross check will compare the pipe config value with
> 0 otherwise.
> 
> v2: Do the cross check with the initial value of encoder_pixel_multiplier (0)
> if the sdvo command fails (and thus keep the warning) (Daniel Vetter)
> 
> Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
Queued for -next, thanks for the patch.
-Daniel
> ---
>  drivers/gpu/drm/i915/intel_sdvo.c | 24 +++++++++++++-----------
>  1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
> index b8e1623..eb2a603 100644
> --- a/drivers/gpu/drm/i915/intel_sdvo.c
> +++ b/drivers/gpu/drm/i915/intel_sdvo.c
> @@ -1357,17 +1357,19 @@ static void intel_sdvo_get_config(struct intel_encoder *encoder,
>  	}
>  
>  	/* Cross check the port pixel multiplier with the sdvo encoder state. */
> -	intel_sdvo_get_value(intel_sdvo, SDVO_CMD_GET_CLOCK_RATE_MULT, &val, 1);
> -	switch (val) {
> -	case SDVO_CLOCK_RATE_MULT_1X:
> -		encoder_pixel_multiplier = 1;
> -		break;
> -	case SDVO_CLOCK_RATE_MULT_2X:
> -		encoder_pixel_multiplier = 2;
> -		break;
> -	case SDVO_CLOCK_RATE_MULT_4X:
> -		encoder_pixel_multiplier = 4;
> -		break;
> +	if (intel_sdvo_get_value(intel_sdvo, SDVO_CMD_GET_CLOCK_RATE_MULT,
> +				 &val, 1)) {
> +		switch (val) {
> +		case SDVO_CLOCK_RATE_MULT_1X:
> +			encoder_pixel_multiplier = 1;
> +			break;
> +		case SDVO_CLOCK_RATE_MULT_2X:
> +			encoder_pixel_multiplier = 2;
> +			break;
> +		case SDVO_CLOCK_RATE_MULT_4X:
> +			encoder_pixel_multiplier = 4;
> +			break;
> +		}
>  	}
>  
>  	if(HAS_PCH_SPLIT(dev))
> -- 
> 1.8.3.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch