Add length check before reading label pointer

dmachard · Feb 9, 2022 · d2979cf · d2979cf
1 parent 5e0e439
commit d2979cf
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/dnsutils/dns.go b/dnsutils/dns.go
@@ -342,6 +342,9 @@ func _ParseLabels(offset int, payload []byte, pointers map[uint16]int) (string,
 		}
 		// label pointer support ?
 		if length>>6 == 3 {
+			if offset+1 >= len(payload) {
+				return "", 0, ErrDecodeDnsLabelTooShort
+			}
 			ptr := binary.BigEndian.Uint16(payload[offset:offset+2]) & 16383
 			_, exist := pointers[ptr]
 			if exist {