- MFH: CVE-2007-1001, integer overflow with invalid wbmp images

NEWS

@@ -1,6 +1,7 @@
 PHP 4                                                                      NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? 2007, Version 4.4.7
+- Fixed CVE-2007-1001, GD wbmp used with invalid image size (Pierre)
 - Fixed bug #40747 (possible crash in session when save_path is out of 
   open_basedir). (Tony)
 

ext/gd/config.m4

@@ -273,7 +273,7 @@ if test "$PHP_GD" = "yes"; then
                  libgd/gdxpm.c libgd/gdfontt.c libgd/gdfonts.c libgd/gdfontmb.c libgd/gdfontl.c \
                  libgd/gdfontg.c libgd/gdtables.c libgd/gdft.c libgd/gdcache.c libgd/gdkanji.c \
                  libgd/wbmp.c libgd/gd_wbmp.c libgd/gdhelpers.c libgd/gd_topal.c libgd/gd_gif_in.c \
-                 libgd/xbm.c libgd/gd_gif_out.c "
+                 libgd/xbm.c libgd/gd_gif_out.c libgd/gd_security.c"
 
 dnl check for fabsf and floorf which are available since C99
   AC_CHECK_FUNCS(fabsf floorf)

ext/gd/libgd/gd_security.c

@@ -0,0 +1,33 @@
+/*
+   * gd_security.c
+   *
+   * Implements buffer overflow check routines.
+   *
+   * Written 2004, Phil Knirsch.
+   * Based on netpbm fixes by Alan Cox.
+   *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+#include "gd.h"
+
+int overflow2(int a, int b)
+{
+	if(a < 0 || b < 0) {
+		php_gd_error("gd warning: one parameter to a memory allocation multiplication is negative, failing operation gracefully\n");
+		return 1;
+	}
+	if(b == 0)
+		return 0;
+	if(a > INT_MAX / b) {
+		php_gd_error("gd warning: product of memory allocation multiplication would exceed INT_MAX, failing operation gracefully\n");
+		return 1;
+	}
+	return 0;
+}

ext/gd/libgd/gdhelpers.h

@@ -21,6 +21,13 @@ extern char *gd_strtok_r(char *s, char *sep, char **state);
 #define gdPFree(ptr)		pefree(ptr, 1)
 #define gdPEstrdup(ptr)		pestrdup(ptr, 1)
 
+/* Returns nonzero if multiplying the two quantities will
+	result in integer overflow. Also returns nonzero if 
+	either quantity is negative. By Phil Knirsch based on
+	netpbm fixes by Alan Cox. */
+
+int overflow2(int a, int b);
+
 #ifdef ZTS
 #define gdMutexDeclare(x) MUTEX_T x
 #define gdMutexSetup(x) x = tsrm_mutex_alloc()

ext/gd/libgd/wbmp.c

@@ -116,6 +116,15 @@ createwbmp (int width, int height, int color)
   if ((wbmp = (Wbmp *) gdMalloc (sizeof (Wbmp))) == NULL)
     return (NULL);
 
+  if (overflow2(sizeof (int), width)) {
+    gdFree(wbmp);
+    return NULL;
+  }
+  if (overflow2(sizeof (int) * width, height)) {
+    gdFree(wbmp);
+    return NULL;
+  }
+
   if ((wbmp->bitmap = (int *) safe_emalloc(sizeof(int), (width * height), 0)) == NULL)
     {
       gdFree (wbmp);
@@ -176,6 +185,13 @@ readwbmp (int (*getin) (void *in), void *in, Wbmp ** return_wbmp)
   printf ("W: %d, H: %d\n", wbmp->width, wbmp->height);
 #endif
 
+  if (overflow2(sizeof (int), wbmp->width) ||
+    overflow2(sizeof (int) * wbmp->width, wbmp->height))
+    {
+      gdFree(wbmp);
+      return (-1);
+    }
+
   if ((wbmp->bitmap = (int *) safe_emalloc(sizeof(int), (wbmp->width * wbmp->height), 0)) == NULL)
     {
       gdFree (wbmp);

ext/gd/tests/createfromwbmp2.phpt

@@ -0,0 +1,47 @@
+--TEST--
+imagecreatefromwbmp with invalid wbmp
+--SKIPIF--
+<?php
+	if (!function_exists('imagecreatefromwbmp')) die("skip gd extension not available\n");
+?>
+--FILE--
+<?php
+$filename = dirname(__FILE__) . '/_tmp.wbmp';
+$fp = fopen($filename,"wb");
+if (!$fp) {
+	exit("Failed to create <$filename>");
+}
+
+//write header
+$c = 0;
+fputs($fp, chr($c), 1);
+fputs($fp, $c, 1);
+
+//write width = 2^32 / 4 + 1
+$c = 0x84;
+fputs($fp, chr($c), 1);
+$c = 0x80;
+fputs($fp, chr($c), 1);
+fputs($fp, chr($c), 1);
+fputs($fp, chr($c), 1);
+$c = 0x01;
+fputs($fp, chr($c), 1);
+
+/*write height = 4*/
+$c = 0x04;
+fputs($fp, chr($c), 1);
+
+/*write some data to cause overflow*/
+for ($i=0; $i<10000; $i++) {
+	fwrite($fp, chr($c), 1);
+}
+
+fclose($fp);
+$im = imagecreatefromwbmp($filename);
+unlink($filename);
+?>
+--EXPECTF--
+Warning: imagecreatefromwbmp() [/phpmanual/function.imagecreatefromwbmp.html]: gd warning: product of memory allocation multiplication would exceed INT_MAX, failing operation gracefully
+ in %s on line %d
+
+Warning: imagecreatefromwbmp() [/phpmanual/function.imagecreatefromwbmp.html]: '%s' is not a valid WBMP file in %s on line %d