Throw on negative label length in `DNSName::isPartOf()`

Found with American Fuzzy Lop and Address Sanitizer.

diff --git a/pdns/dnsname.cc b/pdns/dnsname.cc
index 7111ff18d123159033bc6f08ce70a270a52d22f2..cfc4d4bebe0507b7de44e16335f7f84f7d824781 100644 (file)
--- a/pdns/dnsname.cc
+++ b/pdns/dnsname.cc
@@ -201,6 +201,9 @@ bool DNSName::isPartOf(const DNSName& parent) const
       }
       return true;
     }
+    if (*us < 0) {
+      throw std::out_of_range("negative label length in dnsname");
+    }
   }
   return false;
 }