From nobody Tue Nov 11 22:49:06 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1566241744; cv=none; d=zoho.com; s=zohoarc; b=hstkR6DLy7gV7FOwlCDgTh0nCDkN8j2AHMClH45kXvRJn773EVsg9l9rG9KH0RCJphAp4LZSWp859Gx3TI+LBt2s5LOOXHGJY1IkWHmsA4AEmdzydvZedmQh0o3qHOjBmQ9j4i2UUBbeCuSA3y3aB4gNZedSnTU/1H05yJ+bKno= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1566241744; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=DSn6Qt5IQbatmXqVhpkEMEg3vj6pyZIhw+v7Lvsojxo=; b=P/GmUy2MeCCeSt/9/tSF741XSIgjkC03tMdeekPsNLX53vkSrGxI9+clHFG0NiGWaRM9/PULOxN33cckhV/Rr3tamwNtLsLUuBvVV7hXh9hgI6dQ/7fcYxtRploy86WQeco99Ypa6oH5S8ThYfQgL0qIzHNC54N/wuqfF1IAOJo= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 156624174434227.399111642046705; Mon, 19 Aug 2019 12:09:04 -0700 (PDT) Received: from localhost ([::1]:56720 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hzn1a-0000wv-Lz for importer@patchew.org; Mon, 19 Aug 2019 15:09:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:32817) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hzmpf-0002Hg-7b for qemu-devel@nongnu.org; Mon, 19 Aug 2019 14:56:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hzmpd-0002B0-Po for qemu-devel@nongnu.org; Mon, 19 Aug 2019 14:56:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58074) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hzmpa-00028V-8m; Mon, 19 Aug 2019 14:56:38 -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 9635630860C6; Mon, 19 Aug 2019 18:56:37 +0000 (UTC) Received: from localhost (ovpn-204-64.brq.redhat.com [10.40.204.64]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2B5FC88B1A; Mon, 19 Aug 2019 18:56:36 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Mon, 19 Aug 2019 20:55:56 +0200 Message-Id: <20190819185602.4267-11-mreitz@redhat.com> In-Reply-To: <20190819185602.4267-1-mreitz@redhat.com> References: <20190819185602.4267-1-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 [10.5.110.44]); Mon, 19 Aug 2019 18:56:37 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2 10/16] qcow2: Fix broken snapshot table entries 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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" 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 **er= rp) 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 tabl= e " + "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 snapsho= t " + "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, Error = **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(extra= ); =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(extra= ); 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 tabl= e"); + 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(BlockD= riverState *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(BlockD= riverState *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(BlockD= riverState *bs, =20 return ret; } + result->corruptions +=3D extra_data_dropped; =20 return 0; } --=20 2.21.0