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From 558a81423955eb43a8e73ad01e46d0fee589c44b Mon Sep 17 00:00:00 2001
From: Su Sung Chung <Su.Chung@amd.com>
Date: Thu, 20 Sep 2018 15:03:27 -0400
Subject: [PATCH 5576/5725] drm/amd/display: fix bug of accessing invalid
 memory

[Why]
A loop inside of build_evenly_distributed_points function that traverse through
the array of points become an infinite loop when m_GammaUpdates does not
get assigned to any value.

[How]
In DMColor, clear m_gammaIsValid bit just before writting all Zeromem for
m_GammaUpdates, to prevent calling build_evenly_distributed_points
before m_GammaUpdates gets assigned to some value.

Signed-off-by: Su Sung Chung <Su.Chung@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
---
 drivers/gpu/drm/amd/display/modules/color/color_gamma.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
index 0fe9882..16f7ea8 100644
--- a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
+++ b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
@@ -1071,10 +1071,14 @@ static void build_evenly_distributed_points(
 	struct dividers dividers)
 {
 	struct gamma_pixel *p = points;
-	struct gamma_pixel *p_last = p + numberof_points - 1;
+	struct gamma_pixel *p_last;
 
 	uint32_t i = 0;
 
+	// This function should not gets called with 0 as a parameter
+	ASSERT(numberof_points > 0);
+	p_last = p + numberof_points - 1;
+
 	do {
 		struct fixed31_32 value = dc_fixpt_from_fraction(i,
 			numberof_points - 1);
@@ -1085,7 +1089,7 @@ static void build_evenly_distributed_points(
 
 		++p;
 		++i;
-	} while (i != numberof_points);
+	} while (i < numberof_points);
 
 	p->r = dc_fixpt_div(p_last->r, dividers.divider1);
 	p->g = dc_fixpt_div(p_last->g, dividers.divider1);
-- 
2.7.4