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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 ++++++------
tests/gif/CMakeLists.txt | 1 +
tests/gif/Makemodule.am | 2 ++
tests/gif/php_bug_75571.c | 28 ++++++++++++++++++++++++++++
tests/gif/php_bug_75571.gif | Bin 0 -> 1731 bytes
6 files changed, 38 insertions(+), 6 deletions(-)
create mode 100644 tests/gif/php_bug_75571.c
diff --git a/src/gd_gif_in.c b/src/gd_gif_in.c
index daf26e79..0a8bd717 100644
--- a/src/gd_gif_in.c
+++ b/src/gd_gif_in.c
@@ -335,11 +335,6 @@ BGD_DECLARE(gdImagePtr) gdImageCreateFromGifCtx(gdIOCtxPtr fd)
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 @@ BGD_DECLARE(gdImagePtr) gdImageCreateFromGifCtx(gdIOCtxPtr fd)
}
}
+ 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;
diff --git a/tests/gif/CMakeLists.txt b/tests/gif/CMakeLists.txt
index 2b73749e..e58e6b09 100644
--- a/tests/gif/CMakeLists.txt
+++ b/tests/gif/CMakeLists.txt
@@ -4,6 +4,7 @@ LIST(APPEND TESTS_FILES
bug00227
gif_null
ossfuzz5700
+ php_bug_75571
uninitialized_memory_read
)
diff --git a/tests/gif/Makemodule.am b/tests/gif/Makemodule.am
index 3199438f..5dbeac53 100644
--- a/tests/gif/Makemodule.am
+++ b/tests/gif/Makemodule.am
@@ -4,6 +4,7 @@ libgd_test_programs += \
gif/bug00227 \
gif/gif_null \
gif/ossfuzz5700 \
+ gif/php_bug_75571 \
gif/uninitialized_memory_read
if HAVE_LIBPNG
@@ -26,4 +27,5 @@ EXTRA_DIST += \
gif/bug00066.gif \
gif/bug00066_exp.png \
gif/ossfuzz5700.gif \
+ gif/php_bug_75571.gif \
gif/unitialized_memory_read.gif
diff --git a/tests/gif/php_bug_75571.c b/tests/gif/php_bug_75571.c
new file mode 100644
index 00000000..d4fae3ae
--- /dev/null
+++ b/tests/gif/php_bug_75571.c
@@ -0,0 +1,28 @@
+/**
+ * Test that GIF reading does not loop infinitely
+ *
+ * We are reading a crafted GIF image which has been truncated. This would
+ * trigger an infinite loop formerly, but know bails out early, returning
+ * NULL from gdImageCreateFromGif().
+ *
+ * See also https://bugs.php.net/bug.php?id=75571.
+ */
+
+
+#include "gd.h"
+#include "gdtest.h"
+
+
+int main()
+{
+ gdImagePtr im;
+ FILE *fp;
+
+ fp = gdTestFileOpen2("gif", "php_bug_75571.gif");
+ gdTestAssert(fp != NULL);
+ im = gdImageCreateFromGif(fp);
+ gdTestAssert(im == NULL);
+ fclose(fp);
+
+ return gdNumFailures();
+}
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