From nobody Mon Feb 9 08:57:26 2026 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=1570808139; cv=none; d=zoho.com; s=zohoarc; b=JU83RLIEd4Hf6RShkLZXRTfL6kopv/i6IPLT4WMvWGJIfzElWx9TDuW0JpfGsWduw/P5PeImA5rHkLs+fWQMCvsbNiygy/9vcEzmoUnxjRH07AN29wd0I3nHjT/IZYXOl8W5XAdqsPYrcG2HnInAiXwkbZongloMdP8jDPb3B1c= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1570808139; 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; bh=Vd4uO5pItnslJVdsn/vUXH9GsCdFsW7d5g66+MVW+6E=; b=VpFu2op+M7R411R3Gr0+U4Xu5Z+i3XRu0I1txV1wEoPPgpxlUDeoYagJII2yG2Pqlc48TbzSluuvoEbmp+AIsXg9NpGrV9fy8uAObhoSrfONbbuSFUSxGMb4htp+iCdKAWSVYk0iFLOx8H4YTEGm/F7rzede9s4d3PFYI3bU4bc= 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 1570808139073523.6420977324016; Fri, 11 Oct 2019 08:35:39 -0700 (PDT) Received: from localhost ([::1]:52270 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iIwx6-0007sE-Un for importer@patchew.org; Fri, 11 Oct 2019 11:35:36 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57737) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iIwqJ-0001RS-HF for qemu-devel@nongnu.org; Fri, 11 Oct 2019 11:28:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iIwqI-0006UM-1r for qemu-devel@nongnu.org; Fri, 11 Oct 2019 11:28:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38058) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iIwqE-0006RO-CW; Fri, 11 Oct 2019 11:28:30 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9F7AD300CB26; Fri, 11 Oct 2019 15:28:29 +0000 (UTC) Received: from localhost (ovpn-116-40.ams2.redhat.com [10.36.116.40]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E50E310013D9; Fri, 11 Oct 2019 15:28:28 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v3 04/16] qcow2: Keep unknown extra snapshot data Date: Fri, 11 Oct 2019 17:28:02 +0200 Message-Id: <20191011152814.14791-5-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 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Fri, 11 Oct 2019 15:28:29 +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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" The qcow2 specification says to ignore unknown extra data fields in snapshot table entries. Currently, we discard it whenever we update the image, which is a bit different from "ignore". This patch makes the qcow2 driver keep all unknown extra data fields when updating an image's snapshot table. Signed-off-by: Max Reitz Reviewed-by: Eric Blake --- block/qcow2.h | 5 ++++ block/qcow2-snapshot.c | 61 +++++++++++++++++++++++++++++++++++------- 2 files changed, 56 insertions(+), 10 deletions(-) diff --git a/block/qcow2.h b/block/qcow2.h index 8da1ad11d9..61e5d4ba94 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -61,6 +61,9 @@ * space for snapshot names and IDs */ #define QCOW_MAX_SNAPSHOTS_SIZE (1024 * QCOW_MAX_SNAPSHOTS) =20 +/* Maximum amount of extra data per snapshot table entry to accept */ +#define QCOW_MAX_SNAPSHOT_EXTRA_DATA 1024 + /* Bitmap header extension constraints */ #define QCOW2_MAX_BITMAPS 65535 #define QCOW2_MAX_BITMAP_DIRECTORY_SIZE (1024 * QCOW2_MAX_BITMAPS) @@ -181,6 +184,8 @@ typedef struct QCowSnapshot { uint32_t date_sec; uint32_t date_nsec; uint64_t vm_clock_nsec; + uint32_t extra_data_size; + void *unknown_extra_data; /* Extra data past QCowSnapshotExtraData */ } QCowSnapshot; =20 struct Qcow2Cache; diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index 80d32e4504..120cb7fa09 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -37,6 +37,7 @@ void qcow2_free_snapshots(BlockDriverState *bs) for(i =3D 0; i < s->nb_snapshots; i++) { g_free(s->snapshots[i].name); g_free(s->snapshots[i].id_str); + g_free(s->snapshots[i].unknown_extra_data); } g_free(s->snapshots); s->snapshots =3D NULL; @@ -51,7 +52,6 @@ int qcow2_read_snapshots(BlockDriverState *bs, Error **er= rp) QCowSnapshot *sn; int i, id_str_size, name_size; int64_t offset; - uint32_t extra_data_size; int ret; =20 if (!s->nb_snapshots) { @@ -80,31 +80,53 @@ int qcow2_read_snapshots(BlockDriverState *bs, Error **= errp) sn->date_sec =3D be32_to_cpu(h.date_sec); sn->date_nsec =3D be32_to_cpu(h.date_nsec); sn->vm_clock_nsec =3D be64_to_cpu(h.vm_clock_nsec); - extra_data_size =3D be32_to_cpu(h.extra_data_size); + sn->extra_data_size =3D be32_to_cpu(h.extra_data_size); =20 id_str_size =3D be16_to_cpu(h.id_str_size); name_size =3D be16_to_cpu(h.name_size); =20 - /* Read extra data */ + 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; + } + + /* Read known extra data */ ret =3D bdrv_pread(bs->file, offset, &extra, - MIN(sizeof(extra), extra_data_size)); + MIN(sizeof(extra), sn->extra_data_size)); if (ret < 0) { error_setg_errno(errp, -ret, "Failed to read snapshot table"); goto fail; } - offset +=3D extra_data_size; + offset +=3D MIN(sizeof(extra), sn->extra_data_size); =20 - if (extra_data_size >=3D endof(QCowSnapshotExtraData, - vm_state_size_large)) { + if (sn->extra_data_size >=3D endof(QCowSnapshotExtraData, + vm_state_size_large)) { sn->vm_state_size =3D be64_to_cpu(extra.vm_state_size_large); } =20 - if (extra_data_size >=3D endof(QCowSnapshotExtraData, disk_size)) { + if (sn->extra_data_size >=3D endof(QCowSnapshotExtraData, disk_siz= e)) { sn->disk_size =3D be64_to_cpu(extra.disk_size); } else { sn->disk_size =3D bs->total_sectors * BDRV_SECTOR_SIZE; } =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); + + 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"); + goto fail; + } + offset +=3D unknown_extra_data_size; + } + /* Read snapshot ID */ sn->id_str =3D g_malloc(id_str_size + 1); ret =3D bdrv_pread(bs->file, offset, sn->id_str, id_str_size); @@ -162,7 +184,7 @@ static int qcow2_write_snapshots(BlockDriverState *bs) sn =3D s->snapshots + i; offset =3D ROUND_UP(offset, 8); offset +=3D sizeof(h); - offset +=3D sizeof(extra); + offset +=3D MAX(sizeof(extra), sn->extra_data_size); offset +=3D strlen(sn->id_str); offset +=3D strlen(sn->name); =20 @@ -209,7 +231,8 @@ static int qcow2_write_snapshots(BlockDriverState *bs) h.date_sec =3D cpu_to_be32(sn->date_sec); h.date_nsec =3D cpu_to_be32(sn->date_nsec); h.vm_clock_nsec =3D cpu_to_be64(sn->vm_clock_nsec); - h.extra_data_size =3D cpu_to_be32(sizeof(extra)); + h.extra_data_size =3D cpu_to_be32(MAX(sizeof(extra), + sn->extra_data_size)); =20 memset(&extra, 0, sizeof(extra)); extra.vm_state_size_large =3D cpu_to_be64(sn->vm_state_size); @@ -234,6 +257,22 @@ static int qcow2_write_snapshots(BlockDriverState *bs) } offset +=3D sizeof(extra); =20 + if (sn->extra_data_size > sizeof(extra)) { + size_t unknown_extra_data_size =3D + sn->extra_data_size - sizeof(extra); + + /* qcow2_read_snapshots() ensures no unbounded allocation */ + assert(unknown_extra_data_size <=3D BDRV_REQUEST_MAX_BYTES); + assert(sn->unknown_extra_data); + + ret =3D bdrv_pwrite(bs->file, offset, sn->unknown_extra_data, + unknown_extra_data_size); + if (ret < 0) { + goto fail; + } + offset +=3D unknown_extra_data_size; + } + ret =3D bdrv_pwrite(bs->file, offset, sn->id_str, id_str_size); if (ret < 0) { goto fail; @@ -376,6 +415,7 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSna= pshotInfo *sn_info) sn->date_sec =3D sn_info->date_sec; sn->date_nsec =3D sn_info->date_nsec; sn->vm_clock_nsec =3D sn_info->vm_clock_nsec; + sn->extra_data_size =3D sizeof(QCowSnapshotExtraData); =20 /* Allocate the L1 table of the snapshot and copy the current one ther= e. */ l1_table_offset =3D qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint6= 4_t)); @@ -647,6 +687,7 @@ int qcow2_snapshot_delete(BlockDriverState *bs, * The snapshot is now unused, clean up. If we fail after this point, = we * won't recover but just leak clusters. */ + g_free(sn.unknown_extra_data); g_free(sn.id_str); g_free(sn.name); =20 --=20 2.21.0