Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Su Sung Chung <Su.Chung@amd.com>,
        Aric Cyr <Aric.Cyr@amd.com>,
        Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 005/205] drm/amd/display: fix bug of accessing invalid memory
Date:   Mon, 19 Nov 2018 17:25:12 +0100
Message-Id: <20181119162617.904108535@linuxfoundation.org>
In-Reply-To: <20181119162616.586062722@linuxfoundation.org>
References: <20181119162616.586062722@linuxfoundation.org>
User-Agent: quilt/0.65
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Su Sung Chung <Su.Chung@amd.com>

[ Upstream commit 43c3ff27a47d83d153c4adc088243ba594582bf5 ]

[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>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/amd/display/modules/color/color_gamma.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
+++ b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
@@ -1069,10 +1069,14 @@ static void build_evenly_distributed_poi
 	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);
@@ -1083,7 +1087,7 @@ static void build_evenly_distributed_poi
 
 		++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);