[Spice-devel] [PATCH libcacard 2/2] vreader: Handle read failure

[Jakub Jelen]

On Wed, 2018-08-08 at 16:51 +0200, Marc-André Lureau wrote:
> Hi
> 
> On Tue, Jul 24, 2018 at 8:34 PM, Jason Andryuk <jandryuk at gmail.com>
> wrote:
> > If a command fails, card_status will not match VCARD_DONE.  That
> > will
> > trigger the assert and abort the process.  Instead, handle
> > VCARD_FAIL and
> > return an error in that case.  Client software can then deal with
> > the
> > error, and we continue running to handle future commands.
> > 
> > This can be triggered by removing the physical smartcard mid-
> > operation.
> 
> There are other paths, like invalid instruction on
> cac_common_process_apdu_read()

The invalid instructions should return valid response with error
indicated in SW (status words). The referenced function has the default
VCARD_FAIL value is in the code somehow bogus in case we would like to
fail early or fail to handle some case (?).

The VCARD_FAIL option is really about more serious issues as Jason is
pointing out.

Handling the error here, rather than segfaulting in assert later sounds
like a good idea. But from reading the code, I still can not find a
path where we could encounter this value here.

>From what I see, all the paths here return either VCARD_DONE. Can you
advice during which operation did you encounter this error?

Regards,
-- 
Jakub Jelen
Software Engineer
Security Technologies
Red Hat, Inc.