Fix bug #77988 - heap-buffer-overflow on php_jpg_get16

Author: smalyshev

NEWS

@@ -2,6 +2,10 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? 2019, PHP 7.1.30
 
+- EXIF:
+  . Fixed bug #77988 (heap-buffer-overflow on php_jpg_get16). 
+  (CVE-2019-11040) (Stas)
+
 - GD:
   . Fixed bug #77973 (Uninitialized read in gdImageCreateFromXbm).
   (CVE-2019-11038) (cmb)
@@ -12,11 +16,11 @@ PHP                                                                        NEWS
 
 03 May 2019, PHP 7.1.29
 
-- EXIF
+- EXIF:
   . Fixed bug #77950 (Heap-buffer-overflow in _estrndup via exif_process_IFD_TAG).
   (CVE-2019-11036) (Stas)
 
-- Mail
+- Mail:
   . Fixed bug #77821 (Potential heap corruption in TSendMail()). (cmb)
 
 04 Apr 2019, PHP 7.1.28

ext/exif/exif.c

@@ -3526,6 +3526,8 @@ static int exif_scan_thumbnail(image_info_type *ImageInfo)
 		if (c == 0xFF)
 			return FALSE;
 		marker = c;
+		if (pos>=ImageInfo->Thumbnail.size)
+			return FALSE;
 		length = php_jpg_get16(data+pos);
 		if (length > ImageInfo->Thumbnail.size || pos >= ImageInfo->Thumbnail.size - length) {
 			return FALSE;

ext/exif/tests/bug77988.jpg

@@ -0,0 +1,11 @@
+--TEST--
+Bug #77988 (heap-buffer-overflow on php_jpg_get16)
+--SKIPIF--
+<?php if (!extension_loaded('exif')) print 'skip exif extension not available';?>
+--FILE--
+<?php
+exif_read_data(__DIR__."/bug77988.jpg", 'COMMENT', FALSE, TRUE);
+?>
+DONE
+--EXPECTF--
+DONE