From 2e886046f86d0d6bfc14aab94a881259a081e3f4 Mon Sep 17 00:00:00 2001
From: wilson chen <willson.chenwx@gmail.com>
Date: Fri, 20 Dec 2019 10:12:04 +0800
Subject: [PATCH] Fix #497: gdImageColorMatch Out Of Bounds Write on Heap
 (CVE-2019-6977)

Fixed CVE-2019-6977 and add corresponding testcase.

Original patch by Christoph M. Bechker <cmbecker69@gmx.de>
https://gist.github.com/cmb69/1f36d285eb297ed326f5c821d7aafced

[Retrieved (and updated to remove .gitignore and tests) from:
https://github.com/libgd/libgd/commit/2e886046f86d0d6bfc14aab94a881259a081e3f4]
Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
---
 src/gd_color_match.c                    |  5 ++---
 tests/gdimagecolormatch/.gitignore      |  1 +
 tests/gdimagecolormatch/CMakeLists.txt  |  1 +
 tests/gdimagecolormatch/Makemodule.am   |  1 +
 tests/gdimagecolormatch/cve_2019_6977.c | 25 +++++++++++++++++++++++++
 5 files changed, 30 insertions(+), 3 deletions(-)
 create mode 100644 tests/gdimagecolormatch/cve_2019_6977.c

diff --git a/src/gd_color_match.c b/src/gd_color_match.c
index f0842b69..f0194302 100644
--- a/src/gd_color_match.c
+++ b/src/gd_color_match.c
@@ -31,9 +31,8 @@ BGD_DECLARE(int) gdImageColorMatch (gdImagePtr im1, gdImagePtr im2)
 		return -4; /* At least 1 color must be allocated */
 	}
 
-	buf = (unsigned long *)gdMalloc(sizeof(unsigned long) * 5 * im2->colorsTotal);
-	memset (buf, 0, sizeof(unsigned long) * 5 * im2->colorsTotal );
-
+	buf = (unsigned long *)gdMalloc(sizeof(unsigned long) * 5 * gdMaxColors);
+	memset (buf, 0, sizeof(unsigned long) * 5 * gdMaxColors );
 	for (x=0; x < im1->sx; x++) {
 		for( y=0; y<im1->sy; y++ ) {
 			color = im2->pixels[y][x];