Re: [PATCH] drm/amd/display: Fix potential index out of bounds in color transformation function

["Chung, ChiaHsuan (Tom)" <chiahsuan.chung@amd.com>]

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

On 2/28/2024 5:17 PM, Srinivasan Shanmugam wrote:
> Fixes index out of bounds issue in the color transformation function.
> 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, an error message is
> logged and the function returns false to indicate an error.
>
> Reported by smatch:
> drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_cm_common.c:405 cm_helper_translate_curve_to_hw_format() error: buffer overflow 'output_tf->tf_pts.red' 1025 <= s32max
> drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_cm_common.c:406 cm_helper_translate_curve_to_hw_format() error: buffer overflow 'output_tf->tf_pts.green' 1025 <= s32max
> drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_cm_common.c:407 cm_helper_translate_curve_to_hw_format() error: buffer overflow 'output_tf->tf_pts.blue' 1025 <= s32max
>
> Fixes: b629596072e5 ("drm/amd/display: Build unity lut for shaper")
> Cc: Vitaly Prosyak <vitaly.prosyak@amd.com>
> Cc: Charlene Liu <Charlene.Liu@amd.com>
> Cc: Harry Wentland <harry.wentland@amd.com>
> Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
> Cc: Roman Li <roman.li@amd.com>
> Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
> Cc: Tom Chung <chiahsuan.chung@amd.com>
> Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
> ---
>   drivers/gpu/drm/amd/display/dc/dcn10/dcn10_cm_common.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_cm_common.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_cm_common.c
> index b7e57aa27361..b0d192c6e63e 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_cm_common.c
> +++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_cm_common.c
> @@ -402,6 +402,11 @@ bool cm_helper_translate_curve_to_hw_format(struct dc_context *ctx,
>   				i += increment) {
>   			if (j == hw_points - 1)
>   				break;
> +			if (i >= TRANSFER_FUNC_POINTS) {
> +				DC_LOG_ERROR("Index out of bounds: i=%d, TRANSFER_FUNC_POINTS=%d\n",
> +					     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];