krb5: KDC daemon crash via free() of an uninitialized pointer

The kdchandleprotectednegotiation function in the Key Distribution Center KDC in MIT Kerberos 5 aka krb5 1.8.x, 1.9.x before 1.9.5, and 1.10.x before 1.10.3 attempts to calculate a checksum before verifying that the key type is appropriate for a checksum, which allows remote attackers to execute...