Commit message: * bugfix #70: heap Out-of-bound Read vulnerability in
  rr_frm_str_internal reported by pokerfacett.
CVE: CVE-2020-19860
CWE: CWE-125
Vulnerability description: When ldns version 1.7.1 verifies a zone file, the ldns_rr_new_frm_str_internal function has a heap out of bounds read vulnerability. An attacker can leak information on the heap by constructing a zone file payload.

Project: ldns
File: rr.c

ldns_rr_new_frm_str_internal(ldns_rr **newrr, const char *str,
							 uint32_t default_ttl, const ldns_rdf *origin,
							 ldns_rdf **prev, bool question)
{
	ldns_rr *new;
	const ldns_rr_descriptor *desc;
	ldns_rr_type rr_type;
	ldns_buffer *rr_buf = NULL;
	ldns_buffer *rd_buf = NULL;
	uint32_t ttl_val;
	char  *owner = NULL;
	char  *ttl = NULL;
	ldns_rr_class clas_val;
	char  *clas = NULL;
	char  *type = NULL;
	size_t type_sz;
	char  *rdata = NULL;
	char  *rd = NULL;
	char  *xtok = NULL; /* For RDF types with spaces (i.e. extra tokens) */
	size_t rd_strlen;
	const char *delimiters;
	ssize_t c;
	ldns_rdf *owner_dname;
        const char* endptr;
        int was_unknown_rr_format = 0;
	ldns_status status = LDNS_STATUS_OK;

	/* used for types with unknown number of rdatas */
	bool done;
	bool quoted;

	ldns_rdf *r = NULL;
	uint16_t r_cnt;
	uint16_t r_min;
	uint16_t r_max;
        size_t pre_data_pos;

	uint16_t hex_data_size;
	char *hex_data_str = NULL;
	uint16_t cur_hex_data_size;
	size_t hex_pos = 0;
	uint8_t *hex_data = NULL;

	new = ldns_rr_new();

	owner = LDNS_XMALLOC(char, LDNS_MAX_DOMAINLEN + 1);
	ttl = LDNS_XMALLOC(char, LDNS_TTL_DATALEN);
	clas = LDNS_XMALLOC(char, LDNS_SYNTAX_DATALEN);
	rdata = LDNS_XMALLOC(char, LDNS_MAX_PACKETLEN + 1);
	rr_buf = LDNS_MALLOC(ldns_buffer);
	rd_buf = LDNS_MALLOC(ldns_buffer);
	rd = LDNS_XMALLOC(char, LDNS_MAX_RDFLEN);
	xtok = LDNS_XMALLOC(char, LDNS_MAX_RDFLEN);
	if (rr_buf) {
		rr_buf->_data = NULL;
	}
	if (rd_buf) {
		rd_buf->_data = NULL;
	}
	if (!new || !owner || !ttl || !clas || !rdata ||
			!rr_buf || !rd_buf || !rd || !xtok) {

		goto memerror;
	}

	ldns_buffer_new_frm_data(rr_buf, (char*)str, strlen(str));

	/* split the rr in its parts -1 signals trouble */
	if (ldns_bget_token(rr_buf, owner, "\t\n ", LDNS_MAX_DOMAINLEN) == -1){

		status = LDNS_STATUS_SYNTAX_ERR;
		goto error;
	}

	if (ldns_bget_token(rr_buf, ttl, "\t\n ", LDNS_TTL_DATALEN) == -1) {

		status = LDNS_STATUS_SYNTAX_TTL_ERR;
		goto error;
	}
	ttl_val = (uint32_t) ldns_str2period(ttl, &endptr);

	if (strlen(ttl) > 0 && !isdigit((int) ttl[0])) {
		/* ah, it's not there or something */
		if (default_ttl == 0) {
			ttl_val = LDNS_DEFAULT_TTL;
		} else {
			ttl_val = default_ttl;
		}
		/* we not ASSUMING the TTL is missing and that
		 * the rest of the RR is still there. That is
		 * CLASS TYPE RDATA
		 * so ttl value we read is actually the class
		 */
		clas_val = ldns_get_rr_class_by_name(ttl);
		/* class can be left out too, assume IN, current
		 * token must be type
		 */
		if (clas_val == 0) {
			clas_val = LDNS_RR_CLASS_IN;
			type_sz = strlen(ttl) + 1;
			type = LDNS_XMALLOC(char, type_sz);
			if (!type) {
				goto memerror;
			}
			strlcpy(type, ttl, type_sz);
		}
	} else {
		if (-1 == ldns_bget_token(
				rr_buf, clas, "\t\n ", LDNS_SYNTAX_DATALEN)) {

			status = LDNS_STATUS_SYNTAX_CLASS_ERR;
			goto error;
		}
		clas_val = ldns_get_rr_class_by_name(clas);
		/* class can be left out too, assume IN, current
		 * token must be type
		 */
		if (clas_val == 0) {
			clas_val = LDNS_RR_CLASS_IN;
			type_sz = strlen(clas) + 1;
			type = LDNS_XMALLOC(char, type_sz);
			if (!type) {
				goto memerror;
			}
			strlcpy(type, clas, type_sz);
		}
	}
	/* the rest should still be waiting for us */

	if (!type) {
		type = LDNS_XMALLOC(char, LDNS_SYNTAX_DATALEN);
		if (!type) {
			goto memerror;
		}
		if (-1 == ldns_bget_token(
				rr_buf, type, "\t\n ", LDNS_SYNTAX_DATALEN)) {

			status = LDNS_STATUS_SYNTAX_TYPE_ERR;
			goto error;
		}
	}

	if (ldns_bget_token(rr_buf, rdata, "\0", LDNS_MAX_PACKETLEN) == -1) {
		/* apparently we are done, and it's only a question RR
		 * so do not set status and go to ldnserror here
		 */
	}
	ldns_buffer_new_frm_data(rd_buf, rdata, strlen(rdata));

	if (strlen(owner) <= 1 && strncmp(owner, "@", 1) == 0) {
		if (origin) {
			ldns_rr_set_owner(new, ldns_rdf_clone(origin));
		} else if (prev && *prev) {
			ldns_rr_set_owner(new, ldns_rdf_clone(*prev));
		} else {
			/* default to root */
			ldns_rr_set_owner(new, ldns_dname_new_frm_str("."));
		}

		/* @ also overrides prev */
		if (prev) {
			ldns_rdf_deep_free(*prev);
			*prev = ldns_rdf_clone(ldns_rr_owner(new));
			if (!*prev) {
				goto memerror;
			}
		}
	} else {
		if (strlen(owner) == 0) {
			/* no ownername was given, try prev, if that fails
			 * origin, else default to root */
			if (prev && *prev) {
				ldns_rr_set_owner(new, ldns_rdf_clone(*prev));
			} else if (origin) {
				ldns_rr_set_owner(new, ldns_rdf_clone(origin));
			} else {
				ldns_rr_set_owner(new,
						ldns_dname_new_frm_str("."));
			}
			if(!ldns_rr_owner(new)) {
				goto memerror;
			}
		} else {
			owner_dname = ldns_dname_new_frm_str(owner);
			if (!owner_dname) {
				status = LDNS_STATUS_SYNTAX_ERR;
				goto error;
			}

			ldns_rr_set_owner(new, owner_dname);
			if (!ldns_dname_str_absolute(owner) && origin) {
				if(ldns_dname_cat(ldns_rr_owner(new), origin)
						!= LDNS_STATUS_OK) {

					status = LDNS_STATUS_SYNTAX_ERR;
					goto error;
				}
			}
			if (prev) {
				ldns_rdf_deep_free(*prev);
				*prev = ldns_rdf_clone(ldns_rr_owner(new));
				if (!*prev) {
					goto error;
				}
			}
		}
	}
	LDNS_FREE(owner);

	ldns_rr_set_question(new, question);

	ldns_rr_set_ttl(new, ttl_val);
	LDNS_FREE(ttl);

	ldns_rr_set_class(new, clas_val);
	LDNS_FREE(clas);

	rr_type = ldns_get_rr_type_by_name(type);
	LDNS_FREE(type);

	desc = ldns_rr_descript((uint16_t)rr_type);
	ldns_rr_set_type(new, rr_type);
	if (desc) {
		/* only the rdata remains */
		r_max = ldns_rr_descriptor_maximum(desc);
		r_min = ldns_rr_descriptor_minimum(desc);
	} else {
		r_min = 0;
		r_max = 1;
	}

	for (done = false, r_cnt = 0; !done && r_cnt < r_max; r_cnt++) {
		quoted = false;

		switch (ldns_rr_descriptor_field_type(desc, r_cnt)) {
		case LDNS_RDF_TYPE_B64        :
		case LDNS_RDF_TYPE_HEX        : /* These rdf types may con- */
		case LDNS_RDF_TYPE_LOC        : /* tain whitespace, only if */
		case LDNS_RDF_TYPE_WKS        : /* it is the last rd field. */
		case LDNS_RDF_TYPE_IPSECKEY   :
		case LDNS_RDF_TYPE_AMTRELAY   :
		case LDNS_RDF_TYPE_NSEC       :	if (r_cnt == r_max - 1) {
							delimiters = "\n";
							break;
						}
						/* fallthrough */
		default                       :	delimiters = "\n\t "; 
		}

		if (ldns_rdf_type_maybe_quoted(
				ldns_rr_descriptor_field_type(
				desc, r_cnt)) &&
				ldns_buffer_remaining(rd_buf) > 0){

			/* skip spaces */
			while (*(ldns_buffer_current(rd_buf)) == ' ') {
				ldns_buffer_skip(rd_buf, 1);
			}

			if (*(ldns_buffer_current(rd_buf)) == '\"') {
				delimiters = "\"\0";
				ldns_buffer_skip(rd_buf, 1);
				quoted = true;
			} else if (ldns_rr_descriptor_field_type(desc, r_cnt)
					== LDNS_RDF_TYPE_LONG_STR) {

				status = LDNS_STATUS_SYNTAX_RDATA_ERR;
				goto error;
			}
		}

		/* because number of fields can be variable, we can't rely on
		 * _maximum() only
		 */

		/* skip spaces */
		while (ldns_buffer_position(rd_buf) < ldns_buffer_limit(rd_buf)
				&& *(ldns_buffer_current(rd_buf)) == ' '
				&& !quoted) {

			ldns_buffer_skip(rd_buf, 1);
		}

		pre_data_pos = ldns_buffer_position(rd_buf);
		if (-1 == (c = ldns_bget_token(
				rd_buf, rd, delimiters, LDNS_MAX_RDFLEN))) {

			done = true;
			(void)done; /* we're breaking, so done not read anymore */
			break;
		}
		/* hmmz, rfc3597 specifies that any type can be represented 
		 * with \# method, which can contain spaces...
		 * it does specify size though...
		 */
		rd_strlen = strlen(rd);

		/* unknown RR data */
		if (strncmp(rd, "\\#", 2) == 0 && !quoted &&
				(rd_strlen == 2 || rd[2]==' ')) {

			was_unknown_rr_format = 1;
			/* go back to before \#
			 * and skip it while setting delimiters better
			 */
			ldns_buffer_set_position(rd_buf, pre_data_pos);
			delimiters = "\n\t ";
			(void)ldns_bget_token(rd_buf, rd,
					delimiters, LDNS_MAX_RDFLEN);
			/* read rdata octet length */
			c = ldns_bget_token(rd_buf, rd,
					delimiters, LDNS_MAX_RDFLEN);
			if (c == -1) {
				/* something goes very wrong here */
				status = LDNS_STATUS_SYNTAX_RDATA_ERR;
				goto error;
			}
			hex_data_size = (uint16_t) atoi(rd);
			/* copy hex chars into hex str (2 chars per byte) */
			hex_data_str = LDNS_XMALLOC(char, 2*hex_data_size + 1);
			if (!hex_data_str) {
				/* malloc error */
				goto memerror;
			}
			cur_hex_data_size = 0;
			while(cur_hex_data_size < 2 * hex_data_size) {
				c = ldns_bget_token(rd_buf, rd,
						delimiters, LDNS_MAX_RDFLEN);
				if (c == -1) {
					status = LDNS_STATUS_SYNTAX_RDATA_ERR;
					goto error;
				}
				rd_strlen = strlen(rd);
				if ((size_t)cur_hex_data_size + rd_strlen >
				    2 * (size_t)hex_data_size) {
					status = LDNS_STATUS_SYNTAX_RDATA_ERR;
					goto error;
				}
				strlcpy(hex_data_str + cur_hex_data_size, rd,
						rd_strlen + 1);

				cur_hex_data_size += rd_strlen;
			}
			hex_data_str[cur_hex_data_size] = '\0';

			/* correct the rdf type */
			/* if *we* know the type, interpret it as wireformat */
			if (desc) {
				hex_pos = 0;
				hex_data =
					LDNS_XMALLOC(uint8_t, hex_data_size+2);

				if (!hex_data) {
					goto memerror;
				}
				ldns_write_uint16(hex_data, hex_data_size);
				ldns_hexstring_to_data(
						hex_data + 2, hex_data_str);
				status = ldns_wire2rdf(new, hex_data,
						hex_data_size + 2, &hex_pos);
				if (status != LDNS_STATUS_OK) {
					goto error;
				}
				LDNS_FREE(hex_data);
			} else {
				r = ldns_rdf_new_frm_str(LDNS_RDF_TYPE_HEX,
						hex_data_str);
				if (!r) {
					goto memerror;
				}
				ldns_rdf_set_type(r, LDNS_RDF_TYPE_UNKNOWN);
				if (!ldns_rr_push_rdf(new, r)) {
					goto memerror;
				}
			}
			LDNS_FREE(hex_data_str);

		} else if(rd_strlen > 0 || quoted) {
			/* Normal RR */
			switch(ldns_rr_descriptor_field_type(desc, r_cnt)) {

			case LDNS_RDF_TYPE_HEX:
			case LDNS_RDF_TYPE_B64:
				/* When this is the last rdata field, then the
				 * rest should be read in (cause then these
				 * rdf types may contain spaces).
				 */
				if (r_cnt == r_max - 1) {
					c = ldns_bget_token(rd_buf, xtok,
							"\n", LDNS_MAX_RDFLEN);
					if (c != -1) {
						(void) strncat(rd, xtok,
							LDNS_MAX_RDFLEN -
							strlen(rd) - 1);
					}
				}
				r = ldns_rdf_new_frm_str(
						ldns_rr_descriptor_field_type(
							desc, r_cnt), rd);
				break;

			case LDNS_RDF_TYPE_HIP:
				/*
				 * In presentation format this RDATA type has
				 * three tokens: An algorithm byte, then a
				 * variable length HIT (in hexbytes) and then
				 * a variable length Public Key (in base64).
				 *
				 * We have just read the algorithm, so we need
				 * two more tokens: HIT and Public Key.
				 */
				do {
					/* Read and append HIT */
					if (ldns_bget_token(rd_buf,
							xtok, delimiters,
							LDNS_MAX_RDFLEN) == -1)
						break;

					(void) strncat(rd, " ",
							LDNS_MAX_RDFLEN -
							strlen(rd) - 1);
					(void) strncat(rd, xtok,
							LDNS_MAX_RDFLEN -
							strlen(rd) - 1);

					/* Read and append Public Key*/
					if (ldns_bget_token(rd_buf,
							xtok, delimiters,
							LDNS_MAX_RDFLEN) == -1)
						break;

					(void) strncat(rd, " ",
							LDNS_MAX_RDFLEN -
							strlen(rd) - 1);
					(void) strncat(rd, xtok,
							LDNS_MAX_RDFLEN -
							strlen(rd) - 1);
				} while (false);

				r = ldns_rdf_new_frm_str(
						ldns_rr_descriptor_field_type(
							desc, r_cnt), rd);
				break;

			case LDNS_RDF_TYPE_DNAME:
				r = ldns_rdf_new_frm_str(
						ldns_rr_descriptor_field_type(
							desc, r_cnt), rd);

				/* check if the origin should be used
				 * or concatenated
				 */
				if (r && ldns_rdf_size(r) > 1 &&
						ldns_rdf_data(r)[0] == 1 &&
						ldns_rdf_data(r)[1] == '@') {

					ldns_rdf_deep_free(r);

					r = origin ? ldns_rdf_clone(origin)

					  : ( rr_type == LDNS_RR_TYPE_SOA ?

					      ldns_rdf_clone(
						      ldns_rr_owner(new))

					    : ldns_rdf_new_frm_str(
						    LDNS_RDF_TYPE_DNAME, ".")
					    );

				} else if (r && rd_strlen >= 1 && origin &&
						!ldns_dname_str_absolute(rd)) {

					status = ldns_dname_cat(r, origin);
					if (status != LDNS_STATUS_OK) {
						goto error;
					}
				}
				break;
			default:
				r = ldns_rdf_new_frm_str(
						ldns_rr_descriptor_field_type(
							desc, r_cnt), rd);
				break;
			}
			if (!r) {
				status = LDNS_STATUS_SYNTAX_RDATA_ERR;
				goto error;
			}
			ldns_rr_push_rdf(new, r);
		}
		if (quoted) {
			if (ldns_buffer_available(rd_buf, 1)) {
				ldns_buffer_skip(rd_buf, 1);
			} else {
				done = true;
			}
		}

	} /* for (done = false, r_cnt = 0; !done && r_cnt < r_max; r_cnt++) */
	LDNS_FREE(rd);
	LDNS_FREE(xtok);
	ldns_buffer_free(rr_buf);
	LDNS_FREE(rdata);
	if (ldns_buffer_remaining(rd_buf) > 0) {
		ldns_buffer_free(rd_buf);
		ldns_rr_free(new);
		return LDNS_STATUS_SYNTAX_SUPERFLUOUS_TEXT_ERR;
	}
	ldns_buffer_free(rd_buf);

	if (!question && desc && !was_unknown_rr_format &&
			ldns_rr_rd_count(new) < r_min) {

		ldns_rr_free(new);
		return LDNS_STATUS_SYNTAX_MISSING_VALUE_ERR;
	}

	if (newrr) {
		*newrr = new;
	} else {
		/* Maybe the caller just wanted to see if it would parse? */
		ldns_rr_free(new);
	}
	return LDNS_STATUS_OK;

memerror:
	status = LDNS_STATUS_MEM_ERR;
error:
	if (rd_buf && rd_buf->_data) {
		ldns_buffer_free(rd_buf);
	} else {
		LDNS_FREE(rd_buf);
	}
	if (rr_buf && rr_buf->_data) {
		ldns_buffer_free(rr_buf);
	} else {
		LDNS_FREE(rr_buf);
	}
	LDNS_FREE(type);
	LDNS_FREE(owner);
	LDNS_FREE(ttl);
	LDNS_FREE(clas);
	LDNS_FREE(hex_data);
	LDNS_FREE(hex_data_str);
	LDNS_FREE(xtok);
	LDNS_FREE(rd);
	LDNS_FREE(rdata);
	ldns_rr_free(new);
	return status;
}