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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Thu, 23 Mar 2017 08:43:27 +0100
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References: <20170322204844.446-1-f4bug@amsat.org>
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Subject: Re: [Qemu-devel] [PATCH RESEND 1/3] usb-ccid: make
 ccid_write_data_block() cope with null buffers
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To: Markus Armbruster <armbru@redhat.com>
Cc: Philippe =?ISO-8859-1?Q?Mathieu-Daud=E9?= <f4bug@amsat.org>, Michael Roth <mdroth@linux.vnet.ibm.com>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, Alexander Graf <agraf@suse.de>, qemu-trivial@nongnu.org, qemu-devel@nongnu.org

  Hi,

> > +    if (len =3D=3D 0) {
> > +        return;
>=20
> Correct only if messages without data always have the same meaning as no
> message.  Gerd?

Not a ccid expert, but looking through the code it seems writing a
(reply) data block with status and without payload (data =3D NULL and len
=3D 0) is perfectly fine and can happen in case no (virtual) smartcard is
inserted into the card reader.  Which this patch breaks.  So,

NACK.

cheers,
  Gerd