asn1_der_decoding API misuse

[Florian Weimer]

The comment in gnutls26-2.8.6/lib/minitasn1/decoding.c says this:

  * @errorDescription: null-terminated string contains details when an
  *   error occurred.

However, there are quite a few error returns without previous writes to
the errorDescription buffer.  Either the callers should be change to
initialize the character buffer which is passed to asn1_der_decoding(),
or asn1_der_decoding() should write an empty string to errorDescription
if no description string is available.

-- 
Florian Weimer                <fweimer at bfk.de>
BFK edv-consulting GmbH       http://www.bfk.de/
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