From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:58447) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hBS5O-0004eJ-Km for qemu-devel@nongnu.org; Tue, 02 Apr 2019 18:40:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hBS5N-0006WN-LS for qemu-devel@nongnu.org; Tue, 02 Apr 2019 18:40:54 -0400 References: <20190401140903.19186-1-eblake@redhat.com> <20190401140903.19186-11-eblake@redhat.com> From: Eric Blake Message-ID: Date: Tue, 2 Apr 2019 17:40:47 -0500 MIME-Version: 1.0 In-Reply-To: <20190401140903.19186-11-eblake@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="CNGuY8g3aKdo97p01V0F5h8MDQuM2f60R" Subject: Re: [Qemu-devel] [PULL 10/14] nbd/client: Reject inaccessible tail of inconsistent server List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Vladimir Sementsov-Ogievskiy , "open list:Network Block Dev..." This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --CNGuY8g3aKdo97p01V0F5h8MDQuM2f60R From: Eric Blake To: qemu-devel@nongnu.org Cc: Vladimir Sementsov-Ogievskiy , "open list:Network Block Dev..." Message-ID: Subject: Re: [Qemu-devel] [PULL 10/14] nbd/client: Reject inaccessible tail of inconsistent server References: <20190401140903.19186-1-eblake@redhat.com> <20190401140903.19186-11-eblake@redhat.com> In-Reply-To: <20190401140903.19186-11-eblake@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 4/1/19 9:08 AM, Eric Blake wrote: > The NBD spec suggests that a server should never advertise a size > inconsistent with its minimum block alignment, as that tail is > effectively inaccessible to a compliant client obeying those block > constraints. Since we have a habit of rounding up rather than > truncating, to avoid losing the last few bytes of user input, and we > cannot access the tail when the server advertises bogus block sizing, > abort the connection to alert the server to fix their bug. And > rejecting such servers matches what we already did for a min_block > that was not a power of 2 or which was larger than max_block. >=20 > Does not impact either qemu (which always sends properly aligned > sizes) or nbdkit (which does not send minimum block requirements yet); > so this is mostly aimed at new NBD server implementations, and ensures > that the rest of our code can assume the size is aligned. >=20 > Signed-off-by: Eric Blake > Message-Id: <20190330155704.24191-1-eblake@redhat.com> > Reviewed-by: Vladimir Sementsov-Ogievskiy > --- > nbd/client.c | 8 ++++++++ > 1 file changed, 8 insertions(+) >=20 > diff --git a/nbd/client.c b/nbd/client.c > index de7da48246b..427980bdd22 100644 > --- a/nbd/client.c > +++ b/nbd/client.c > @@ -426,6 +426,14 @@ static int nbd_opt_info_or_go(QIOChannel *ioc, uin= t32_t opt, > nbd_send_opt_abort(ioc); > return -1; > } > + if (info->min_block && > + !QEMU_IS_ALIGNED(info->size, info->min_block)) { > + error_setg(errp, "export size %" PRIu64 "is not multip= le of " Missing a space in the error message. If I have any other patches worthy of an -rc3 pull request, I'll do the obvious fix then. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org --CNGuY8g3aKdo97p01V0F5h8MDQuM2f60R Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAlyj5O8ACgkQp6FrSiUn Q2r1+Qf8DbJYoUdnJz+EB7+SOsRyNanOPtI597GCpM4b1h3iv0x4nbXuR8df/dd2 q8JPBqpuzK7hT0utacPeQUhcsL9OupPYwjn/z0dFBUpBnBf1y+Yb1SkhsiCk7Wyh TFfVRkTnj1WtkUyAqVaBT9/jAOYFNmqTWDNEirly6BUI8asSjOawAvxo5oph4hYN KgqUTS9wczwQGMA58HWDxtHEeUwq0izYGZrRhmqKHCZkhKNNXh44g/2uksHU7b9r r3N/wteBGUx8jGer9MT9OL3lF3KD9rJNmQ/3K9zCHGmQZNWNdoVlsq/CdVd0a/vM Q2hvmJReZbk6/jrLo31TQPcchs/umA== =5NCN -----END PGP SIGNATURE----- --CNGuY8g3aKdo97p01V0F5h8MDQuM2f60R--