[PATCH AUTOSEL 6.6 18/83] drm/amd/display: Fix Coverity INTEGER_OVERFLOW within decide_fallback_link_setting_max_bw_policy

Sasha Levin
2024-08-01T00:22:44Z

From: Hersen Wu <hersenxs.wu@amd.com>

[ Upstream commit 83c0c8361347cf43937348e8ca0a487679c003ae ]

[Why]
For addtion (uint8_t) variable + constant 1,
coverity generates message below:
Truncation due to cast operation on "cur_idx + 1" from
32 to 8 bits.

Then Coverity assume result is 32 bits value be saved into
8 bits variable. When result is used as index to access
array, Coverity suspects index invalid.

[How]
Change varaible type to uint32_t.

Reviewed-by: Alex Hung <alex.hung@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Hersen Wu <hersenxs.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
index 9a0beaf601f87..16f4865e4246d 100644
--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
@@ -528,7 +528,7 @@ static bool decide_fallback_link_setting_max_bw_policy(
struct dc_link_settings *cur,
enum link_training_result training_result)
{
- uint8_t cur_idx = 0, next_idx;
+ uint32_t cur_idx = 0, next_idx;
bool found = false;

if (training_result == LINK_TRAINING_ABORT)
--
2.43.0