From abf5ed2271756125b8e5e8fc47cca00e05d725ee Mon Sep 17 00:00:00 2001
From: Leslie Shi <Yuliang.Shi@amd.com>
Date: Fri, 17 Jun 2022 16:02:27 +0800
Subject: [PATCH] drm/amdkcl: Fix 64 bit wraparound resulting in illegal drm
mode
[Why]
For m = drm_display_mode{.clock = 533250, .htotal = 4000, .vtotal = 2222},
common_rates[i] = 60000, the result of target_vtotal is 2221. This cause
wraparound of variable target_vtotal_diff.
[How]
Skip the loop if target_vtotal less than m->vtotal
Signed-off-by: Leslie Shi <Yuliang.Shi@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index b3821f79da034..0950633ebd721 100755
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -9218,6 +9218,10 @@ static uint add_fs_modes(struct amdgpu_dm_connector *aconnector)
num = (unsigned long long)m->clock * 1000 * 1000;
den = common_rates[i] * (unsigned long long)m->htotal;
target_vtotal = div_u64(num, den);
+
+ if (target_vtotal < m->vtotal)
+ continue;
+
target_vtotal_diff = target_vtotal - m->vtotal;
/* Check for illegal modes */
--
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