From a918020c03880e12ac9f38e11a4a3789491a5f85 Mon Sep 17 00:00:00 2001
From: "Christoph M. Becker" <cmbecker69@gmx.de>
Date: Wed, 12 Dec 2018 16:00:59 +0100
Subject: Fix #77269: Potential unsigned underflow in gdImageScale

Belatedly, we're porting the respective upstream patch[1].

[1] <https://github.com/libgd/libgd/commit/60bfb401ad5a4a8ae995dcd36372fe15c71e1a35>
---
 ext/gd/libgd/gd_interpolation.c | 18 +++++++++---------
 ext/gd/tests/bug77269.phpt      | 21 +++++++++++++++++++++
 2 files changed, 30 insertions(+), 9 deletions(-)
 create mode 100644 ext/gd/tests/bug77269.phpt

diff --git a/ext/gd/libgd/gd_interpolation.c b/ext/gd/libgd/gd_interpolation.c
index 1c151b5509..d456c0a596 100644
--- a/ext/gd/libgd/gd_interpolation.c
+++ b/ext/gd/libgd/gd_interpolation.c
@@ -880,8 +880,13 @@ static inline LineContribType * _gdContributionsAlloc(unsigned int line_length,
 {
 	unsigned int u = 0;
 	LineContribType *res;
-	int overflow_error = 0;
+	size_t weights_size;
 
+	if (overflow2(windows_size, sizeof(double))) {
+		return NULL;
+	} else {
+		weights_size = windows_size * sizeof(double);
+	}
 	res = (LineContribType *) gdMalloc(sizeof(LineContribType));
 	if (!res) {
 		return NULL;
@@ -898,15 +903,10 @@ static inline LineContribType * _gdContributionsAlloc(unsigned int line_length,
 		return NULL;
 	}
 	for (u = 0 ; u < line_length ; u++) {
-		if (overflow2(windows_size, sizeof(double))) {
-			overflow_error = 1;
-		} else {
-			res->ContribRow[u].Weights = (double *) gdMalloc(windows_size * sizeof(double));
-		}
-		if (overflow_error == 1 || res->ContribRow[u].Weights == NULL) {
+		res->ContribRow[u].Weights = (double *) gdMalloc(weights_size);
+		if (res->ContribRow[u].Weights == NULL) {
 			unsigned int i;
-			u--;
-			for (i=0;i<=u;i++) {
+			for (i=0;i<u;i++) {
 				gdFree(res->ContribRow[i].Weights);
 			}
 			gdFree(res->ContribRow);
diff --git a/ext/gd/tests/bug77269.phpt b/ext/gd/tests/bug77269.phpt
new file mode 100644
index 0000000000..3bdc23e80a
--- /dev/null
+++ b/ext/gd/tests/bug77269.phpt
@@ -0,0 +1,21 @@
+--TEST--
+Bug #77269 (Potential unsigned underflow in gdImageScale)
+--SKIPIF--
+<?php
+if (!extension_loaded('gd')) die('skip gd extension not available');
+if (getenv("SKIP_SLOW_TESTS")) die("skip slow test");
+?>
+--INI--
+memory_limit=2G
+--FILE--
+<?php
+$im = imagecreate(2**28, 1);
+if(is_resource($im)) {
+	imagescale($im, 1, 1, IMG_TRIANGLE);
+}
+?>
+===DONE===
+--EXPECTF--
+Warning: imagecreate():%S product of memory allocation multiplication would exceed INT_MAX, failing operation gracefully
+ in %s on line %d
+===DONE===
-- 
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