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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 D078FC3A5A2 for ; Tue, 3 Sep 2019 13:35:51 +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 A6CF723431 for ; Tue, 3 Sep 2019 13:35:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A6CF723431 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; 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Tue, 3 Sep 2019 13:27:12 +0000 (UTC) Received: from localhost.localdomain (ovpn-116-195.ams2.redhat.com [10.36.116.195]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2FC9160166; Tue, 3 Sep 2019 13:27:11 +0000 (UTC) Date: Tue, 3 Sep 2019 15:27:09 +0200 From: Kevin Wolf To: Peter Lieven Message-ID: <20190903132709.GH4582@localhost.localdomain> References: <20190902152413.14070-1-pl@kamp.de> <20190903130254.GG4582@localhost.localdomain> <95ed6572-b423-ddf2-c2a1-53ae09d9f767@kamp.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <95ed6572-b423-ddf2-c2a1-53ae09d9f767@kamp.de> User-Agent: Mutt/1.12.0 (2019-05-25) 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 [10.5.110.43]); Tue, 03 Sep 2019 13:27:13 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH V2] block/vhdx: add check for truncated image files 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: codyprime@gmail.com, mreitz@redhat.com, jhf@kamp.de, qemu-block@nongnu.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 03.09.2019 um 15:10 hat Peter Lieven geschrieben: > Am 03.09.19 um 15:02 schrieb Kevin Wolf: > > Am 02.09.2019 um 17:24 hat Peter Lieven geschrieben: > > > qemu is currently not able to detect truncated vhdx image files. > > > Add a basic check if all allocated blocks are reachable at open and > > > report all errors during bdrv_co_check. > > > > > > Signed-off-by: Peter Lieven > > > --- > > > V2: - add error reporting [Kevin] > > > - use bdrv_getlength instead of bdrv_get_allocated_file_size [Kevin] > > > - factor out BAT entry check and add error reporting for region > > > overlaps > > > - already check on vhdx_open > > > > > > block/vhdx.c | 85 +++++++++++++++++++++++++++++++++++++++++----------- > > > 1 file changed, 68 insertions(+), 17 deletions(-) > > > > > > diff --git a/block/vhdx.c b/block/vhdx.c > > > index 6a09d0a55c..6afba5e8c2 100644 > > > --- a/block/vhdx.c > > > +++ b/block/vhdx.c > > > @@ -24,6 +24,7 @@ > > > #include "qemu/option.h" > > > #include "qemu/crc32c.h" > > > #include "qemu/bswap.h" > > > +#include "qemu/error-report.h" > > > #include "vhdx.h" > > > #include "migration/blocker.h" > > > #include "qemu/uuid.h" > > > @@ -235,6 +236,9 @@ static int vhdx_region_check(BDRVVHDXState *s, uint64_t start, uint64_t length) > > > end = start + length; > > > QLIST_FOREACH(r, &s->regions, entries) { > > > if (!((start >= r->end) || (end <= r->start))) { > > > + error_report("VHDX region %" PRIu64 "-%" PRIu64 " overlaps with " > > > + "region %" PRIu64 "-%." PRIu64, start, end, r->start, > > > + r->end); > > > ret = -EINVAL; > > > goto exit; > > > } > > > @@ -877,6 +881,60 @@ static void vhdx_calc_bat_entries(BDRVVHDXState *s) > > > } > > > +static int vhdx_check_bat_entries(BlockDriverState *bs, int *errcnt) > > > +{ > > > + BDRVVHDXState *s = bs->opaque; > > > + int64_t image_file_size = bdrv_getlength(bs->file->bs); > > > + uint64_t payblocks = s->chunk_ratio; > > > + int i, ret = 0; > > bdrv_getlength() can fail. It's probably better to error out immediately > > instead of reporting that every BAT entry is > -1. > > > > > + for (i = 0; i < s->bat_entries; i++) { > > s->bat_entries is uint32_t, so i should probably be the same. > > > > > + if ((s->bat[i] & VHDX_BAT_STATE_BIT_MASK) == > > > + PAYLOAD_BLOCK_FULLY_PRESENT) { > > > + /* > > > + * Check if fully allocated BAT entries do not reside after > > > + * end of the image file. > > > + */ > > > + if ((s->bat[i] & VHDX_BAT_FILE_OFF_MASK) + s->block_size > > > > + image_file_size) { > > Didn't we want to introduce an overflow check before making this check? > > Something like if (bat_offset > UINT64_MAX - s->block_size)? > > Sorry, i missed that. > > The bat entries are UINT64_T so this check will always be false for the > default block size of 1MB. In fact we should check for > > bat_offset > INT64_MAX - s->block_size > > right? Hm, VHDX_BAT_FILE_OFF_MASK is 0xFFFFFFFFFFF00000ULL, so 2^64 - 1 MB. With a block size of 1 MB, this check would trigger because the offset would be one byte higher than allowed (because offset + block_size would be 0). For larger block sizes, it's more obvious that we can run into this case. As for INT64_MAX, I'm not sure if it's strictly necessary because the code seems to use unsigned variables everywhere. But it feels safer and shouldn't make any difference in practice, so I agree with using it. Kevin