From nobody Sun Feb 8 17:47:53 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=1555343836; cv=none; d=zoho.com; s=zohoarc; b=G23ItAVVqzCfEXn791OA3YxdcaiPMpYM8gEylRKpeLuTk58d5UHy+zqF0jy6p94u4GsZwGPLtE7pE5UGfaohUaoUweCKYonU8IEZVwPkaoXtywrCtmEYVN6b0V+4cN1ExOomWwXR9x+j/K5Clj/EfaoDQn6600oBNTC3T9bi7eA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1555343836; 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=3QXxwniWwxx4GwDROssemUhq547788AOUdzNASnLTPM=; b=PyJf9Iy8EpbvcjCdzKXbvMUDrm8X89RtOM4V61Xe2rozMYrVww0m5kL0gPam6nSM0GcPhXJyPgasoT9Nq2HIWVKQ4/OceoKEEN54ZXjiEuHkaZ+y9G5NsIFO38myRX/ldSXDydzxtbKqWbLlFkTkwXp70msJEYDCxRETCXazWiQ= 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 1555343836820154.72971728109405; Mon, 15 Apr 2019 08:57:16 -0700 (PDT) Received: from localhost ([127.0.0.1]:52189 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hG3yq-0000Xo-Tp for importer@patchew.org; Mon, 15 Apr 2019 11:57:12 -0400 Received: from eggs.gnu.org ([209.51.188.92]:47703) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hG3x5-0007fq-7o for qemu-devel@nongnu.org; Mon, 15 Apr 2019 11:55:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hG3x3-0003Ug-1l for qemu-devel@nongnu.org; Mon, 15 Apr 2019 11:55:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60395) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hG3wx-0003Nj-Av; Mon, 15 Apr 2019 11:55:15 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 71CA681E0F; Mon, 15 Apr 2019 15:55:14 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-117-113.ams2.redhat.com [10.36.117.113]) by smtp.corp.redhat.com (Postfix) with ESMTP id 605DA60123; Mon, 15 Apr 2019 15:55:10 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Date: Mon, 15 Apr 2019 17:54:50 +0200 Message-Id: <20190415155452.5115-3-kwolf@redhat.com> In-Reply-To: <20190415155452.5115-1-kwolf@redhat.com> References: <20190415155452.5115-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 15 Apr 2019 15:55:14 +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 for-4.0? 2/4] qcow2: Fix preallocation bdrv_pwrite to wrong file X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" With an external data file, preallocate_co() must write the final byte to the external data file, not to the qcow2 image file. This is harmless for preallocation of newly created images (only the qcow2 file size is increased to the virtual disk size while it should be much smaller), but with preallocated resize, it could in theory cause visible corruption if the metadata of the image is larger than the data (e.g. lots of bitmaps). Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- block/qcow2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/qcow2.c b/block/qcow2.c index c8400e9712..dfac74c264 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2772,7 +2772,7 @@ static int coroutine_fn preallocate_co(BlockDriverSta= te *bs, uint64_t offset, */ if (host_offset !=3D 0) { uint8_t data =3D 0; - ret =3D bdrv_pwrite(bs->file, (host_offset + cur_bytes) - 1, + ret =3D bdrv_pwrite(s->data_file, (host_offset + cur_bytes) - 1, &data, 1); if (ret < 0) { return ret; --=20 2.20.1