commit 1731e3c: [Minor] Fix parsing of the very long TXT records

[Vsevolod Stakhov]

Author: Vsevolod Stakhov
Date: 2022-01-06 15:03:23 +0000
URL: https://github.com/rspamd/rspamd/commit/1731e3c94597f2e5797bf8dcb2197da701560a0e (HEAD -> master)

[Minor] Fix parsing of the very long TXT records

---
 contrib/librdns/parse.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/contrib/librdns/parse.c b/contrib/librdns/parse.c
index 1a9c01838..e9fb85e98 100644
--- a/contrib/librdns/parse.c
+++ b/contrib/librdns/parse.c
@@ -351,10 +351,6 @@ rdns_parse_rr (struct rdns_resolver *resolver,
 	case DNS_T_TXT:
 	case DNS_T_SPF:
 		if (datalen <= *remain) {
-			if (datalen > UINT16_MAX / 2) {
-				rdns_info ("too large datalen; domain %s", rep->requested_name);
-				return -1;
-			}
 			elt->content.txt.data = malloc(datalen + 1);
 			if (elt->content.txt.data == NULL) {
 				rdns_err ("failed to allocate %d bytes for TXT record; domain %s",
@@ -417,20 +413,24 @@ rdns_parse_rr (struct rdns_resolver *resolver,
 			rdns_info ("stripped dns reply while reading TLSA record; domain %s", rep->requested_name);
 			return -1;
 		}
-		if (datalen > UINT16_MAX / 2) {
+
+		if (datalen > *remain) {
 			rdns_info ("too large datalen; domain %s", rep->requested_name);
 			return -1;
 		}
+
 		GET8 (elt->content.tlsa.usage);
 		GET8 (elt->content.tlsa.selector);
 		GET8 (elt->content.tlsa.match_type);
 		datalen -= 3;
+
 		elt->content.tlsa.data = malloc (datalen);
 		if (elt->content.tlsa.data == NULL) {
 			rdns_err ("failed to allocate %d bytes for TLSA record; domain %s",
 					(int)datalen + 1, rep->requested_name);
 			return -1;
 		}
+
 		elt->content.tlsa.datalen = datalen;
 		memcpy (elt->content.tlsa.data, p, datalen);
 		p += datalen;