Patch 0001-Fix-potential-unsigned-underflow.patch for GD related Bug #73866

Patch version 2017-01-05 10:29 UTC

• 2017-01-05 10:29 UTC [diff to current]

Developer: ondrej@php.net

From adf2ea35cf3332652d0211d5efa83e5a36454b01 Mon Sep 17 00:00:00 2001
From: "Christoph M. Becker" <cmbecker69@gmx.de>
Date: Sat, 6 Aug 2016 10:08:53 +0200
Subject: [PATCH 1/4] Fix potential unsigned underflow

No need to decrease `u`, so we don't do it. While we're at it, we also factor
out the overflow check of the loop, what improves performance and readability.

This issue has been reported by Stefan Esser to security@libgd.org.
---
 ext/gd/libgd/gd_interpolation.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/ext/gd/libgd/gd_interpolation.c b/ext/gd/libgd/gd_interpolation.c
index 1c151b5..b86a47f 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 +903,11 @@ 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);
-- 
2.1.4