#61 Use after free in authenticate_user_krb5pwd()

[Johan Ymerson]

In verify_krb5_user() krb5_kt_close() is called under certain conditions, but krb5_kt_close() is also called from the top level function authenticate_user_krb5pwd() after calling verify_krb5_user().
This leads to a use after free, since kbr5_kt_close() free up memory pointed to in the keytab struct and
the next call to krb5_kt_close() will dereference pointers in that (now freed) memory.
This leads to a segmentation fault with recent versions of MIT Kerberos.

Patch to fix this attached.

[Paul Wise]

FYI I've just added this patch to the Debian package of mod_auth_kerb in response to Debian bug #934043.

[Joakim Tjernlund]

This makes mod_auth_kerb load when built against mit-krb5-1.18.2
Not run tested yet