Fix integer overflows on 32-bits

Author: smalyshev

ext/exif/exif.c

@@ -3567,19 +3567,19 @@ static int exif_process_IFD_in_TIFF(image_info_type *ImageInfo, size_t dir_offse
 	tag_table_type tag_table = exif_get_tag_table(section_index);
 
 	if (ImageInfo->ifd_nesting_level > MAX_IFD_NESTING_LEVEL) {
-                return FALSE;
-        }
+		return FALSE;
+	}
 
-	if (ImageInfo->FileSize >= dir_offset+2) {
+	if (ImageInfo->FileSize >= 2 && ImageInfo->FileSize - 2 >= dir_offset) {
 		sn = exif_file_sections_add(ImageInfo, M_PSEUDO, 2, NULL);
 #ifdef EXIF_DEBUG
 		exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Read from TIFF: filesize(x%04X), IFD dir(x%04X + x%04X)", ImageInfo->FileSize, dir_offset, 2);
 #endif
 		php_stream_seek(ImageInfo->infile, dir_offset, SEEK_SET); /* we do not know the order of sections */
 		php_stream_read(ImageInfo->infile, (char*)ImageInfo->file.list[sn].data, 2);
 		num_entries = php_ifd_get16u(ImageInfo->file.list[sn].data, ImageInfo->motorola_intel);
-		dir_size = 2/*num dir entries*/ +12/*length of entry*/*num_entries +4/* offset to next ifd (points to thumbnail or NULL)*/;
-		if (ImageInfo->FileSize >= dir_offset+dir_size) {
+		dir_size = 2/*num dir entries*/ +12/*length of entry*/*(size_t)num_entries +4/* offset to next ifd (points to thumbnail or NULL)*/;
+		if (ImageInfo->FileSize >= dir_size && ImageInfo->FileSize - dir_size >= dir_offset) {
 #ifdef EXIF_DEBUG
 			exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Read from TIFF: filesize(x%04X), IFD dir(x%04X + x%04X), IFD entries(%d)", ImageInfo->FileSize, dir_offset+2, dir_size-2, num_entries);
 #endif
@@ -3662,9 +3662,9 @@ static int exif_process_IFD_in_TIFF(image_info_type *ImageInfo, size_t dir_offse
 					}
 				}
 			}
-			if (ImageInfo->FileSize >= dir_offset + ImageInfo->file.list[sn].size) {
+			if (ImageInfo->FileSize >= ImageInfo->file.list[sn].size && ImageInfo->FileSize - ImageInfo->file.list[sn].size >= dir_offset) {
 				if (ifd_size > dir_size) {
-					if (dir_offset + ifd_size > ImageInfo->FileSize) {
+					if (ImageInfo->FileSize < ifd_size || dir_offset > ImageInfo->FileSize - ifd_size) {
 						exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_WARNING, "Error in TIFF: filesize(x%04X) less than size of IFD(x%04X + x%04X)", ImageInfo->FileSize, dir_offset, ifd_size);
 						return FALSE;
 					}