Fix for CVE-2017-10168
Backported for 5.4 without test and binary patch


From d2274b01cbbadf5516b3ea87ad76fbae18834007 Mon Sep 17 00:00:00 2001
From: "Christoph M. Becker" <cmbecker69@gmx.de>
Date: Sat, 17 Dec 2016 17:06:58 +0100
Subject: [PATCH] Fix #73869: Signed Integer Overflow gd_io.c

GD2 stores the number of horizontal and vertical chunks as words (i.e. 2
byte unsigned). These values are multiplied and assigned to an int when
reading the image, what can cause integer overflows. We have to avoid
that, and also make sure that either chunk count is actually greater
than zero. If illegal chunk counts are detected, we bail out from
reading the image.

(cherry picked from commit 5b5d9db3988b829e0b121b74bb3947f01c2796a1)
---
 ext/gd/libgd/gd_gd2.c      |   4 ++++
 ext/gd/tests/bug73869.phpt |  19 +++++++++++++++++++
 ext/gd/tests/bug73869a.gd2 | Bin 0 -> 92 bytes
 ext/gd/tests/bug73869b.gd2 | Bin 0 -> 18 bytes
 4 files changed, 23 insertions(+)
 create mode 100644 ext/gd/tests/bug73869.phpt
 create mode 100644 ext/gd/tests/bug73869a.gd2
 create mode 100644 ext/gd/tests/bug73869b.gd2

diff --git a/ext/gd/libgd/gd_gd2.c b/ext/gd/libgd/gd_gd2.c
index 196b785..3eba6b3 100644
--- a/ext/gd/libgd/gd_gd2.c
+++ b/ext/gd/libgd/gd_gd2.c
@@ -136,6 +136,10 @@ static int _gd2GetHeader(gdIOCtxPtr in, int *sx, int *sy, int *cs, int *vers, in
 	GD2_DBG(php_gd_error("%d Chunks vertically", *ncy));
 
 	if (gd2_compressed(*fmt)) {
+		if (*ncx <= 0 || *ncy <= 0 || *ncx > INT_MAX / *ncy) {
+			GD2_DBG(printf ("Illegal chunk counts: %d * %d\n", *ncx, *ncy));
+			goto fail1;
+		}
 		nc = (*ncx) * (*ncy);
 		GD2_DBG(php_gd_error("Reading %d chunk index entries", nc));
 		if (overflow2(sizeof(t_chunk_info), nc)) {
-- 
2.1.4