Commit message: Fix bug #78793
CVE: CVE-2019-11050
CWE: CWE-125
Vulnerability description: When PHP EXIF extension is parsing EXIF information from an image, e.g. via exif_read_data() function, in PHP versions 7.2.x below 7.2.26, 7.3.x below 7.3.13 and 7.4.0 it is possible to supply it with data what will cause it to read past the allocated buffer. This may lead to information disclosure or crash.

Project: php-src
File: exif.c

static int exif_process_IFD_in_MAKERNOTE(image_info_type *ImageInfo, char * value_ptr, int value_len, char *offset_base, size_t IFDlength, size_t displacement)
{
	size_t i;
	int de, section_index = SECTION_MAKERNOTE;
	int NumDirEntries, old_motorola_intel;
#ifdef KALLE_0
	int offset_diff;
#endif
	const maker_note_type *maker_note;
	char *dir_start;
	int data_len;

	for (i=0; i<=sizeof(maker_note_array)/sizeof(maker_note_type); i++) {
		if (i==sizeof(maker_note_array)/sizeof(maker_note_type)) {
#ifdef EXIF_DEBUG
			exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "No maker note data found. Detected maker: %s (length = %d)", ImageInfo->make, strlen(ImageInfo->make));
#endif
			/* unknown manufacturer, not an error, use it as a string */
			return TRUE;
		}

		maker_note = maker_note_array+i;

		/*exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "check (%s,%s)", maker_note->make?maker_note->make:"", maker_note->model?maker_note->model:"");*/
		if (maker_note->make && (!ImageInfo->make || strcmp(maker_note->make, ImageInfo->make)))
			continue;
		if (maker_note->model && (!ImageInfo->model || strcmp(maker_note->model, ImageInfo->model)))
			continue;
		if (maker_note->id_string && value_len >= maker_note->id_string_len
				&& strncmp(maker_note->id_string, value_ptr, maker_note->id_string_len))
			continue;
		break;
	}

	if (value_len < 2 || maker_note->offset >= value_len - 1) {
		/* Do not go past the value end */
		exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "IFD data too short: 0x%04X offset 0x%04X", value_len, maker_note->offset);
		return FALSE;
	}

	dir_start = value_ptr + maker_note->offset;

#ifdef EXIF_DEBUG
	exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Process %s @x%04X + 0x%04X=%d: %s", exif_get_sectionname(section_index), (int)dir_start-(int)offset_base+maker_note->offset+displacement, value_len, value_len, exif_char_dump(value_ptr, value_len, (int)dir_start-(int)offset_base+maker_note->offset+displacement));
#endif

	ImageInfo->sections_found |= FOUND_MAKERNOTE;

	old_motorola_intel = ImageInfo->motorola_intel;
	switch (maker_note->byte_order) {
		case MN_ORDER_INTEL:
			ImageInfo->motorola_intel = 0;
			break;
		case MN_ORDER_MOTOROLA:
			ImageInfo->motorola_intel = 1;
			break;
		default:
		case MN_ORDER_NORMAL:
			break;
	}

	NumDirEntries = php_ifd_get16u(dir_start, ImageInfo->motorola_intel);

	switch (maker_note->offset_mode) {
		case MN_OFFSET_MAKER:
			offset_base = value_ptr;
			data_len = value_len;
			break;
#ifdef KALLE_0
		case MN_OFFSET_GUESS:
			if (maker_note->offset + 10 + 4 >= value_len) {
				/* Can not read dir_start+10 since it's beyond value end */
				exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "IFD data too short: 0x%04X", value_len);
				return FALSE;
			}
			offset_diff = 2 + NumDirEntries*12 + 4 - php_ifd_get32u(dir_start+10, ImageInfo->motorola_intel);
#ifdef EXIF_DEBUG
			exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Using automatic offset correction: 0x%04X", ((int)dir_start-(int)offset_base+maker_note->offset+displacement) + offset_diff);
#endif
			if (offset_diff < 0 || offset_diff >= value_len ) {
				exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "IFD data bad offset: 0x%04X length 0x%04X", offset_diff, value_len);
				return FALSE;
			}
			offset_base = value_ptr + offset_diff;
			data_len = value_len - offset_diff;
			break;
#endif
		default:
		case MN_OFFSET_NORMAL:
			data_len = value_len;
			break;
	}

	if ((2+NumDirEntries*12) > value_len) {
		exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "Illegal IFD size: 2 + 0x%04X*12 = 0x%04X > 0x%04X", NumDirEntries, 2+NumDirEntries*12, value_len);
		return FALSE;
	}
	if ((dir_start - value_ptr) > value_len - (2+NumDirEntries*12)) {
		exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "Illegal IFD size: 0x%04X > 0x%04X", (dir_start - value_ptr) + (2+NumDirEntries*12), value_len);
		return FALSE;
	}

	for (de=0;de<NumDirEntries;de++) {
		if (!exif_process_IFD_TAG(ImageInfo, dir_start + 2 + 12 * de,
								  offset_base, data_len, displacement, section_index, 0, maker_note->tag_table)) {
			return FALSE;
		}
	}
	ImageInfo->motorola_intel = old_motorola_intel;
/*	NextDirOffset (must be NULL) = php_ifd_get32u(dir_start+2+12*de, ImageInfo->motorola_intel);*/
#ifdef EXIF_DEBUG
	exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Subsection %s done", exif_get_sectionname(SECTION_MAKERNOTE));
#endif
	return TRUE;
}