The sanity check for tag length in a callback request
was broken in two ways:
It checked for a negative value, but not a large positive
value.
It did not set taglen to -1, to indicate to the code that
it should not be used.
This patch fixes both of these issues.
Reported by: rtm@lcs.mit.edu
Tested by: rtm@lcs.mit.edu
PR: 260266
MFC after: 2 weeks
d9931c2561