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Backported for 5.4 without test and binary patch
From 8d6e9588671136837533fe3785657c31c5b52767 Mon Sep 17 00:00:00 2001
From: "Christoph M. Becker" <cmbecker69@gmx.de>
Date: Wed, 29 Nov 2017 18:52:33 +0100
Subject: [PATCH] Fixed bug #75571: 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.
---
ext/gd/libgd/gd_gif_in.c | 10 +++++-----
ext/gd/tests/bug75571.gif | Bin 0 -> 1731 bytes
ext/gd/tests/bug75571.phpt | 15 +++++++++++++++
3 files changed, 20 insertions(+), 5 deletions(-)
create mode 100644 ext/gd/tests/bug75571.gif
create mode 100644 ext/gd/tests/bug75571.phpt
diff --git a/ext/gd/libgd/gd_gif_in.c b/ext/gd/libgd/gd_gif_in.c
index e0f0fe3..16776d3 100644
--- a/ext/gd/libgd/gd_gif_in.c
+++ b/ext/gd/libgd/gd_gif_in.c
@@ -261,10 +261,6 @@ terminated:
if (!im) {
return 0;
}
- if (!im->colorsTotal) {
- gdImageDestroy(im);
- return 0;
- }
/* Check for open colors at the end, so
we can reduce colorsTotal and ultimately
BitsPerPixel */
@@ -275,6 +271,10 @@ terminated:
break;
}
}
+ if (!im->colorsTotal) {
+ gdImageDestroy(im);
+ return 0;
+ }
return im;
}
/* }}} */
@@ -375,7 +375,7 @@ 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;
--
2.1.4
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