Floating point exception in AuthMD5

[Alexander Gutkin]

   Hi,

	It seems that AuthMD5::password_to_key (and probably
the same applies to the privacy class) is not very robust with regard to
use of empty password strings. Here is what I get under gdb if I try to
add user with an empty authentication password:

Program received signal SIGFPE, Arithmetic exception.
0x08145384 in AuthMD5::password_to_key(unsigned char const*, unsigned,
unsigned char const*, unsigned, unsigned char*, unsigned*)
(this=0x81e5850,
    password=0x81ea440 "", password_len=0, engine_id=0x81e57a8 "\200",
    engine_id_len=13, key=0xbfffe8f0 "P╓\036\b", key_len=0xbfffe934)
    at auth_priv.cpp:947

         I think a nicer way would have been to propagate error back to
the user of add_usm_user(...) method, although the lack of checks in that
function seems fair.

				Regards,
					Alexander.