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

[Srinivasan Shanmugam]

Fixes index out of bounds issue in
`cm_helper_translate_curve_to_degamma_hw_format` 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 the function returns
false to indicate an error.

Reported by smatch:
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_cm_common.c:594 cm_helper_translate_curve_to_degamma_hw_format() error: buffer overflow 'output_tf->tf_pts.red' 1025 <= s32max
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_cm_common.c:595 cm_helper_translate_curve_to_degamma_hw_format() error: buffer overflow 'output_tf->tf_pts.green' 1025 <= s32max
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_cm_common.c:596 cm_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/dcn10/dcn10_cm_common.c | 2 ++
 1 file changed, 2 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 0b49362f71b0..eaed5d1c398a 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
@@ -591,6 +591,8 @@ bool cm_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];
-- 
2.34.1