[krbdev.mit.edu #8717] racecondition in posix platformAccess code path

[Greg Hudson via RT]

How would an attacker gain access to the path to a user's home 
directory?  The path to .k5login can alternatively be configured via 
[libdefaults] k5login_directory, but it seems very unlikely that an 
administrator would set that path to something underneath /tmp or 
similar.

Also, what would be the adverse security impact of making the .k5login 
appear to exist at one moment but then be unopenable when the code 
tries to open it?  It seems like that would just cause the localauth 
operation to deny access.

I moderated this through because I don't think there is actually a 
security issue, but please use krbcore-security at mit.edu to report bugs 
which you believe are exploitable.