This patch is adapted from commit a11f47475e6443b7f32d21f2271f28f417e2ac04 and
fixes CVE-2018-5711.

From a11f47475e6443b7f32d21f2271f28f417e2ac04 Mon Sep 17 00:00:00 2001
From: "Christoph M. Becker" <cmbecker69@gmx.de>
Date: Wed, 29 Nov 2017 19:37:38 +0100
Subject: [PATCH] Fix #420: Potential infinite loop in gdImageCreateFromGifCtx

Due to a signedness confusion in `GetCode_` a corrupt GIF file can
trigger an infinite loop.  Furthermore we make sure that a GIF without
any palette entries is treated as invalid *after* open palette entries
have been removed.

CVE-2018-5711

See also https://bugs.php.net/bug.php?id=75571.
---
 src/gd_gif_in.c             |  12 ++++++------
 1 file changed, 38 insertions(+), 6 deletions(-)

diff --git a/src/gd_gif_in.c b/src/gd_gif_in.c
index daf26e7..0a8bd71 100644
--- a/src/gd_gif_in.c
+++ b/src/gd_gif_in.c
@@ -335,11 +335,6 @@ terminated:
 		return 0;
 	}
 
-	if(!im->colorsTotal) {
-		gdImageDestroy(im);
-		return 0;
-	}
-
 	/* Check for open colors at the end, so
 	 * we can reduce colorsTotal and ultimately
 	 * BitsPerPixel */
@@ -351,6 +346,11 @@ terminated:
 		}
 	}
 
+	if(!im->colorsTotal) {
+		gdImageDestroy(im);
+		return 0;
+	}
+
 	return im;
 }
 
@@ -447,7 +447,7 @@ static int
 GetCode_(gdIOCtx *fd, CODE_STATIC_DATA *scd, int code_size, int flag, int *ZeroDataBlockP)
 {
 	int i, j, ret;
-	unsigned char count;
+	int count;
 
 	if(flag) {
 		scd->curbit = 0;

-- 
2.13.6

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<tr><td><span title='2017-04-17 21:35:38 +0200'>2017-04-17</span></td><td><a href='/guix/commit/gnu/packages/libunistring.scm?id=b100e0e89ebd1a6e73d6be4e354dd684abb057a4'>gnu: libunistring: Fix make check issues on multi-core machines.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2017-01-06 17:14:41 -0500'>2017-01-06</span></td><td><a href='/guix/commit/gnu/packages/libunistring.scm?id=74288230ea8b2310495dc2739f39ceadcc143fd0'>Merge branch 'master' into core-updates</a></td><td>Leo Famulari</td></tr>
<tr><td><span title='2016-12-07 10:23:17 +0100'>2016-12-07</span></td><td><a href='/guix/commit/gnu/packages/libunistring.scm?id=d788fcd3ba2a780393765013451fcace9bb10800'>gnu: libunistring: support mingw: propagate libiconv if needed.</a><span class='msg-avail'>...</span></td><td>Jan Nieuwenhuizen</td></tr>
<tr><td><span title='2016-12-03 19:35:27 +0200'>2016-12-03</span></td><td><a href='/guix/commit/gnu/packages/libunistring.scm?id=d54c0bfde4fed2160689dc50b659c76cff9724be'>gnu: libunistring: Update to 0.9.7.</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>
"target".</a><span class='msg-avail'>...</span></td><td>Andy Wingo</td></tr>
<tr><td><span title='2017-05-16 14:41:01 +0200'>2017-05-16</span></td><td><a href='/guix/commit/gnu/tests.scm?id=b09a8da4a2e50845a297e041762f3ff9e649c047'>bootloader: Add extlinux support.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2017-05-04 18:05:05 +0200'>2017-05-04</span></td><td><a href='/guix/commit/gnu/tests.scm?id=67d84d6335ae84ac7c217061570e6b968060073c'>tests: Use 'fold-module-public-variables' for discovery.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-05-03 23:50:15 +0200'>2017-05-03</span></td><td><a href='/guix/commit/gnu/tests.scm?id=cd903ef7871170d3c4eced45418459d293ef48a7'>Add (guix discovery).</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-04-01 00:45:18 +0200'>2017-04-01</span></td><td><a href='/guix/commit/gnu/tests.scm?id=892d9089a88abaa2ef1127f16308d03f4f08a4ce'>tests: Introduce 'simple-operating-system' and use it.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-07-12 22:47:08 +0200'>2016-07-12</span></td><td><a href='/guix/commit/gnu/tests.scm?id=a91c3fc727ba90d8c9b91f67fb672da2e6b877ad'>services: &lt;shepherd-service&gt; no longer has an 'imported-modules' field.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>