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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 3EEBBC47404 for ; Fri, 11 Oct 2019 15:37:37 +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 12A59206A1 for ; Fri, 11 Oct 2019 15:37:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 12A59206A1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:52296 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iIwz1-0002fb-UI for qemu-devel@archiver.kernel.org; Fri, 11 Oct 2019 11:37:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57891) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iIwqZ-0001iX-IZ for qemu-devel@nongnu.org; Fri, 11 Oct 2019 11:28:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iIwqY-0006dS-5J for qemu-devel@nongnu.org; Fri, 11 Oct 2019 11:28:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59658) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iIwqV-0006bi-64; Fri, 11 Oct 2019 11:28:47 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6EFC02BF02; Fri, 11 Oct 2019 15:28:46 +0000 (UTC) Received: from localhost (ovpn-116-40.ams2.redhat.com [10.36.116.40]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0C2E45D9CA; Fri, 11 Oct 2019 15:28:45 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v3 10/16] qcow2: Fix broken snapshot table entries Date: Fri, 11 Oct 2019 17:28:08 +0200 Message-Id: <20191011152814.14791-11-mreitz@redhat.com> In-Reply-To: <20191011152814.14791-1-mreitz@redhat.com> References: <20191011152814.14791-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Fri, 11 Oct 2019 15:28:46 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 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: Kevin Wolf , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The only case where we currently reject snapshot table entries is when they have too much extra data. Fix them with qemu-img check -r all by counting it as a corruption, reducing their extra_data_size, and then letting qcow2_check_fix_snapshot_table() do the rest. Signed-off-by: Max Reitz Reviewed-by: Eric Blake --- block/qcow2-snapshot.c | 67 +++++++++++++++++++++++++++++++++++------- 1 file changed, 56 insertions(+), 11 deletions(-) diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index b526a8f819..53dc1635ec 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -44,7 +44,23 @@ void qcow2_free_snapshots(BlockDriverState *bs) s->nb_snapshots =3D 0; } =20 -int qcow2_read_snapshots(BlockDriverState *bs, Error **errp) +/* + * If @repair is true, try to repair a broken snapshot table instead + * of just returning an error: + * + * - If there were snapshots with too much extra metadata, increment + * *extra_data_dropped for each. + * This requires the caller to eventually rewrite the whole snapshot + * table, which requires cluster allocation. Therefore, this should + * be done only after qcow2_check_refcounts() made sure the refcount + * structures are valid. + * (In the meantime, the image is still valid because + * qcow2_check_refcounts() does not do anything with snapshots' + * extra data.) + */ +static int qcow2_do_read_snapshots(BlockDriverState *bs, bool repair, + int *extra_data_dropped, + Error **errp) { BDRVQcow2State *s =3D bs->opaque; QCowSnapshotHeader h; @@ -64,6 +80,8 @@ int qcow2_read_snapshots(BlockDriverState *bs, Error **= errp) s->snapshots =3D g_new0(QCowSnapshot, s->nb_snapshots); =20 for(i =3D 0; i < s->nb_snapshots; i++) { + bool truncate_unknown_extra_data =3D false; + /* Read statically sized part of the snapshot header */ offset =3D ROUND_UP(offset, 8); ret =3D bdrv_pread(bs->file, offset, &h, sizeof(h)); @@ -86,10 +104,21 @@ int qcow2_read_snapshots(BlockDriverState *bs, Error= **errp) name_size =3D be16_to_cpu(h.name_size); =20 if (sn->extra_data_size > QCOW_MAX_SNAPSHOT_EXTRA_DATA) { - ret =3D -EFBIG; - error_setg(errp, "Too much extra metadata in snapshot table = " - "entry %i", i); - goto fail; + if (!repair) { + ret =3D -EFBIG; + error_setg(errp, "Too much extra metadata in snapshot ta= ble " + "entry %i", i); + error_append_hint(errp, "You can force-remove this extra= " + "metadata with qemu-img check -r all\n= "); + goto fail; + } + + fprintf(stderr, "Discarding too much extra metadata in snaps= hot " + "table entry %i (%" PRIu32 " > %u)\n", + i, sn->extra_data_size, QCOW_MAX_SNAPSHOT_EXTRA_DATA= ); + + (*extra_data_dropped)++; + truncate_unknown_extra_data =3D true; } =20 /* Read known extra data */ @@ -113,18 +142,26 @@ int qcow2_read_snapshots(BlockDriverState *bs, Erro= r **errp) } =20 if (sn->extra_data_size > sizeof(extra)) { - /* Store unknown extra data */ - size_t unknown_extra_data_size =3D - sn->extra_data_size - sizeof(extra); + uint64_t extra_data_end; + size_t unknown_extra_data_size; + + extra_data_end =3D offset + sn->extra_data_size - sizeof(ext= ra); =20 + if (truncate_unknown_extra_data) { + sn->extra_data_size =3D QCOW_MAX_SNAPSHOT_EXTRA_DATA; + } + + /* Store unknown extra data */ + unknown_extra_data_size =3D sn->extra_data_size - sizeof(ext= ra); sn->unknown_extra_data =3D g_malloc(unknown_extra_data_size)= ; ret =3D bdrv_pread(bs->file, offset, sn->unknown_extra_data, unknown_extra_data_size); if (ret < 0) { - error_setg_errno(errp, -ret, "Failed to read snapshot ta= ble"); + error_setg_errno(errp, -ret, + "Failed to read snapshot table"); goto fail; } - offset +=3D unknown_extra_data_size; + offset =3D extra_data_end; } =20 /* Read snapshot ID */ @@ -163,6 +200,11 @@ fail: return ret; } =20 +int qcow2_read_snapshots(BlockDriverState *bs, Error **errp) +{ + return qcow2_do_read_snapshots(bs, false, NULL, errp); +} + /* add at the end of the file a new list of snapshots */ int qcow2_write_snapshots(BlockDriverState *bs) { @@ -328,6 +370,7 @@ int coroutine_fn qcow2_check_read_snapshot_table(Bloc= kDriverState *bs, { BDRVQcow2State *s =3D bs->opaque; Error *local_err =3D NULL; + int extra_data_dropped =3D 0; int ret; struct { uint32_t nb_snapshots; @@ -363,7 +406,8 @@ int coroutine_fn qcow2_check_read_snapshot_table(Bloc= kDriverState *bs, } =20 qemu_co_mutex_unlock(&s->lock); - ret =3D qcow2_read_snapshots(bs, &local_err); + ret =3D qcow2_do_read_snapshots(bs, fix & BDRV_FIX_ERRORS, + &extra_data_dropped, &local_err); qemu_co_mutex_lock(&s->lock); if (ret < 0) { result->check_errors++; @@ -376,6 +420,7 @@ int coroutine_fn qcow2_check_read_snapshot_table(Bloc= kDriverState *bs, =20 return ret; } + result->corruptions +=3D extra_data_dropped; =20 return 0; } --=20 2.21.0