From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:37043) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gy3L0-0002bk-D4 for qemu-devel@nongnu.org; Sun, 24 Feb 2019 18:37:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gy3Kz-0003Lo-3N for qemu-devel@nongnu.org; Sun, 24 Feb 2019 18:37:38 -0500 Date: Mon, 25 Feb 2019 10:37:11 +1100 From: David Gibson Message-ID: <20190224233711.GD7668@umbus.fritz.box> References: <20190214043916.22128-1-david@gibson.dropbear.id.au> <20190214043916.22128-3-david@gibson.dropbear.id.au> <20190222100822.73515a4d@bahia.lan> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="osDK9TLjxFScVI/L" Content-Disposition: inline In-Reply-To: <20190222100822.73515a4d@bahia.lan> Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/5] virtio-balloon: Corrections to address verification List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: mst@redhat.com, qemu-devel@nongnu.org, David Hildenbrand , qemu-ppc@nongnu.org --osDK9TLjxFScVI/L Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Feb 22, 2019 at 10:08:22AM +0100, Greg Kurz wrote: > On Thu, 14 Feb 2019 15:39:13 +1100 > David Gibson wrote: >=20 > > The virtio-balloon device's verification of the address given to it by = the > > guest has a number of faults: > > * The addresses here are guest physical addresses, which should be > > 'hwaddr' rather than 'ram_addr_t' (the distinction is admittedly > > pretty subtle and confusing) > > * We don't check for section.mr being NULL, which is the main way t= hat > > memory_region_find() reports basic failures. We really need to c= heck > > that before looking at any other section fields, because > > memory_region_find() doesn't initialize them on the failure path > > * We're passing a length of '1' to memory_region_find(), but really= the > > guest is requesting that we put the entire page into the balloon, > > so it makes more sense to call it with BALLOON_PAGE_SIZE > >=20 > > Signed-off-by: David Gibson > > Reviewed-by: David Hildenbrand > > Reviewed-by: Michael S. Tsirkin > > --- > > hw/virtio/virtio-balloon.c | 17 ++++++++++------- > > 1 file changed, 10 insertions(+), 7 deletions(-) > >=20 > > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > > index 43af521884..eb357824d8 100644 > > --- a/hw/virtio/virtio-balloon.c > > +++ b/hw/virtio/virtio-balloon.c > > @@ -221,17 +221,20 @@ static void virtio_balloon_handle_output(VirtIODe= vice *vdev, VirtQueue *vq) > > } > > =20 > > while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4= ) =3D=3D 4) { > > - ram_addr_t pa; > > - ram_addr_t addr; > > + hwaddr pa; > > + hwaddr addr; > > int p =3D virtio_ldl_p(vdev, &pfn); > > =20 > > - pa =3D (ram_addr_t) p << VIRTIO_BALLOON_PFN_SHIFT; > > + pa =3D (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT; > > offset +=3D 4; > > =20 > > - /* FIXME: remove get_system_memory(), but how? */ > > - section =3D memory_region_find(get_system_memory(), pa, 1); > > - if (!int128_nz(section.size) || > > - !memory_region_is_ram(section.mr) || > > + section =3D memory_region_find(get_system_memory(), pa, > > + BALLOON_PAGE_SIZE); > > + if (!section.mr) { > > + trace_virtio_balloon_bad_addr(pa); > > + continue; > > + } >=20 > memory_region_unref(section.mr) with section.mr =3D=3D NULL is safe and > resolves to a nop. Not sure you need a separate if to handle this > case. memory_region_is_ram() and friends are not, however - they will dereference their argument unconditionally. >=20 > Apart from that, >=20 > Reviewed-by: Greg Kurz >=20 > > + if (!memory_region_is_ram(section.mr) || > > memory_region_is_rom(section.mr) || > > memory_region_is_romd(section.mr)) { > > trace_virtio_balloon_bad_addr(pa); >=20 --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --osDK9TLjxFScVI/L Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAlxzKqcACgkQbDjKyiDZ s5I+uA/+OBU3C+aU6Re9845pogF2aT27JBooyD04Zej5Ni12kEnwvwwlbmLAkzEW qV2IrYNN7WK7PI/go/K01tbrLvYWwOXZ+hN4AJOWKC/urj4IcyquHXVD5KWF3Vy4 /IK03lUt8kjiTSptaG15TzaoFU9S9MSAyyt1Ebs/hJk8cr03/Ej+OGEZLRY5tPRQ Q3oiw/RAl5v848Fo0YkaG8j5XdqsZmnHpvKISYBrcCxrPCDi/cHoqmtfEVZe1VkX 3VXp3FsopcxicD/KAD9GMQ9/721r69izl1hbhA4VRE8/u2wTeDPIa57jsBT4/CIh oC4nYZhqzRw3itBZHAbZ8MXaaVC8nPBw+8wVaOzqXn+xB/UBRrpu9vOmcdXRRMBq wcl7dQjRziszxTKAUTiMMzVWiBfxh3SPP5s2vyyRaiJRCwEKstnHeMmdPrCHKGe0 OavrdohFGK0zS1nCGKNOkZ5OvbxkWj5hoNI0kTc98hXcyDgT/Mqmo54nCy0Gvla1 mUz3mq6hh+3DOL8AsZHZ0K8Hlhl53we9Z72RnwM4bcpVmNADKUt7XnS9WqkME/fC r3tNmFUg9uqRqdc8qwruEvaNl3DD0HevLed7yLigg8mjVeW6Lvp9xZQp4bpP4vdY uDP8B4tlBHpnB0Q6Z+Vo5pcnt7+O6MQP2kqSWnHeOwdMMntAJcs= =0758 -----END PGP SIGNATURE----- --osDK9TLjxFScVI/L--