From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF9EBC76191 for ; Thu, 18 Jul 2019 06:02:38 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8C7C12173E for ; Thu, 18 Jul 2019 06:02:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="UW3ot8pn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8C7C12173E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34488 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hnzUz-0005CK-Eo for qemu-devel@archiver.kernel.org; Thu, 18 Jul 2019 02:02:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41713) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hnzSt-0006og-Rm for qemu-devel@nongnu.org; Thu, 18 Jul 2019 02:00:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hnzSs-0004Du-FA for qemu-devel@nongnu.org; Thu, 18 Jul 2019 02:00:27 -0400 Received: from ozlabs.org ([2401:3900:2:1::2]:40539) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hnzSq-0004CC-RS; Thu, 18 Jul 2019 02:00:26 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 45q3Q96GDQz9sNC; Thu, 18 Jul 2019 16:00:17 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1563429617; bh=1X/NmsV4EjPSdjca9icaOm/4RcWjWOcDmnAbmOEMfV4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UW3ot8pnHFbkycl3ZE68pdrDbgL0OnB+/e/klHhGGWvJuEGBxVbJx1f50lvtlROrm zwVetDNAIPG5IcLJFfxDz1/jdFjlJL5bvlllgwzXwB2AO0LKPX8frC9F0JoAbN61yj Ci4ljqE81AdOeA2Y2z6OAgd4Qu11zqLNDF5uFxUw= Date: Thu, 18 Jul 2019 13:50:32 +1000 From: David Gibson To: David Hildenbrand Message-ID: <20190718035032.GC8468@umbus.fritz.box> References: <20190717103550.24657-1-david@redhat.com> <20190717103550.24657-2-david@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="69pVuxX8awAiJ7fD" Content-Disposition: inline In-Reply-To: <20190717103550.24657-2-david@redhat.com> User-Agent: Mutt/1.12.0 (2019-05-25) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2401:3900:2:1::2 Subject: Re: [Qemu-devel] [PATCH-for-4.1 v2 1/3] virtio-balloon: fix QEMU crashes on pagesize > BALLOON_PAGE_SIZE X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Igor Mammedov , qemu-stable@nongnu.org, qemu-devel@nongnu.org, Stefan Hajnoczi , "Michael S . Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --69pVuxX8awAiJ7fD Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 17, 2019 at 12:35:48PM +0200, David Hildenbrand wrote: > We are using the wrong functions to set/clear bits, effectively touching > multiple bits, writing out of range of the bitmap, resulting in memory > corruptions. We have to use set_bit()/clear_bit() instead. >=20 > Can easily be reproduced by starting a qemu guest on hugetlbfs memory, > inflating the balloon. QEMU crashes. This never could have worked > properly - especially, also pages would have been discarded when the > first sub-page would be inflated (the whole bitmap would be set). >=20 > While testing I realized, that on hugetlbfs it is pretty much impossible > to discard a page - the guest just frees the 4k sub-pages in random order > most of the time. I was only able to discard a hugepage a handful of > times - so I hope that now works correctly. >=20 > Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE < > host page size") > Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption > with inflates & deflates") > Cc: qemu-stable@nongnu.org #v4.0.0 > Cc: Stefan Hajnoczi > Cc: David Gibson > Cc: Michael S. Tsirkin > Cc: Igor Mammedov > Signed-off-by: David Hildenbrand Ahem. You can pass me the brown paper bag now. Acked-by: David Gibson > --- > hw/virtio/virtio-balloon.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) >=20 > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > index e85d1c0d5c..669067d661 100644 > --- a/hw/virtio/virtio-balloon.c > +++ b/hw/virtio/virtio-balloon.c > @@ -94,9 +94,8 @@ static void balloon_inflate_page(VirtIOBalloon *balloon, > balloon->pbp->base =3D host_page_base; > } > =20 > - bitmap_set(balloon->pbp->bitmap, > - (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE, > - subpages); > + set_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE, > + balloon->pbp->bitmap); > =20 > if (bitmap_full(balloon->pbp->bitmap, subpages)) { > /* We've accumulated a full host page, we can actually discard > @@ -140,9 +139,8 @@ static void balloon_deflate_page(VirtIOBalloon *ballo= on, > * for a guest to do this in practice, but handle it anyway, > * since getting it wrong could mean discarding memory the > * guest is still using. */ > - bitmap_clear(balloon->pbp->bitmap, > - (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SI= ZE, > - subpages); > + clear_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE, > + balloon->pbp->bitmap); > =20 > if (bitmap_empty(balloon->pbp->bitmap, subpages)) { > g_free(balloon->pbp); --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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