[PATCH] drm/amd/display: Fix index out of bounds in DCN30 degamma hardware format translation

[Chung, ChiaHsuan (Tom)]

Reviewed-by: Tom Chung <chiahsuan.chung at amd.com>

On 7/21/2024 2:22 PM, Srinivasan Shanmugam wrote:
> This commit addresses a potential index out of bounds issue in the
> `cm3_helper_translate_curve_to_degamma_hw_format` function in the DCN30
> color  management module. The issue could occur when the index 'i'
> exceeds the  number of transfer function points (TRANSFER_FUNC_POINTS).
>
> The fix adds a check to ensure 'i' is within bounds before accessing the
> transfer function points. If 'i' is out of bounds, the function returns
> false to indicate an error.
>
> Reported by smatch:
> drivers/gpu/drm/amd/amdgpu/../display/dc/dcn30/dcn30_cm_common.c:338 cm3_helper_translate_curve_to_degamma_hw_format() error: buffer overflow 'output_tf->tf_pts.red' 1025 <= s32max
> drivers/gpu/drm/amd/amdgpu/../display/dc/dcn30/dcn30_cm_common.c:339 cm3_helper_translate_curve_to_degamma_hw_format() error: buffer overflow 'output_tf->tf_pts.green' 1025 <= s32max
> drivers/gpu/drm/amd/amdgpu/../display/dc/dcn30/dcn30_cm_common.c:340 cm3_helper_translate_curve_to_degamma_hw_format() error: buffer overflow 'output_tf->tf_pts.blue' 1025 <= s32max
>
> Cc: Tom Chung <chiahsuan.chung at amd.com>
> Cc: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
> Cc: Roman Li <roman.li at amd.com>
> Cc: Alex Hung <alex.hung at amd.com>
> Cc: Aurabindo Pillai <aurabindo.pillai at amd.com>
> Cc: Harry Wentland <harry.wentland at amd.com>
> Cc: Hamza Mahfooz <hamza.mahfooz at amd.com>
> Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
> ---
>   drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c
> index ef7d75f6ab93..f31f0e3abfc0 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c
> +++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c
> @@ -337,6 +337,8 @@ bool cm3_helper_translate_curve_to_degamma_hw_format(
>   				i += increment) {
>   			if (j == hw_points - 1)
>   				break;
> +			if (i >= TRANSFER_FUNC_POINTS)
> +				return false;
>   			rgb_resulted[j].red = output_tf->tf_pts.red[i];
>   			rgb_resulted[j].green = output_tf->tf_pts.green[i];
>   			rgb_resulted[j].blue = output_tf->tf_pts.blue[i];