pull up r20304 from trunk

pull up r20304 from trunk

 r20304@cathode-dark-space:  raeburn | 2008-04-18 15:31:47 -0400
 ticket: new
 subject: fix possible buffer overrun in handling generic-error return
 target_version: 1.6.5
 tags: pullup

 Jeff Altman reported this, based on a crash seen in KfW in the wild.

 The krb5_data handle used to describe the message field returned by the KDC is
 not null-terminated, but we use a "%s" format to incorporate it into an error
 message string.  In the right circumstances, garbage bytes can be pulled into
 the string, or a memory fault may result.

 However, as this is in the error-reporting part of the client-side code for
 fetching new credentials, it's a relatively minor DoS attack only, not a
 serious security exposure.  Should be fixed in the next releases, though.

ticket: 5944
version_fixed: 1.6.4

git-svn-id: svn://anonsvn.mit.edu/krb5/branches/krb5-1-6@20521 dc483132-0cff-0310-8789-dd5450dbe970