From nobody Mon Feb 9 23:01:14 2026 Delivered-To: importer@patchew.org Received-SPF: temperror (zoho.com: Error in retrieving data from DNS) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=temperror (zoho.com: Error in retrieving data from DNS) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1510680575018242.43474162049984; Tue, 14 Nov 2017 09:29:35 -0800 (PST) Received: from localhost ([::1]:32768 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eEf1I-0002Lv-IW for importer@patchew.org; Tue, 14 Nov 2017 12:29:08 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53539) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eEewo-0005Pd-ES for qemu-devel@nongnu.org; Tue, 14 Nov 2017 12:24:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eEewn-00048k-8y for qemu-devel@nongnu.org; Tue, 14 Nov 2017 12:24:30 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41290) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eEewk-00044b-Jb; Tue, 14 Nov 2017 12:24:26 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BE3C05DA03; Tue, 14 Nov 2017 17:24:25 +0000 (UTC) Received: from localhost (unknown [10.40.205.72]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 393564C7; Tue, 14 Nov 2017 17:24:24 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Tue, 14 Nov 2017 18:23:59 +0100 Message-Id: <20171114172417.7654-3-mreitz@redhat.com> In-Reply-To: <20171114172417.7654-1-mreitz@redhat.com> References: <20171114172417.7654-1-mreitz@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Tue, 14 Nov 2017 17:24:25 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 02/20] qcow2: Prevent allocating L2 tables at offset 0 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: Kevin Wolf , Peter Maydell , Alberto Garcia , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_6 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Alberto Garcia If the refcount data is corrupted then we can end up trying to allocate a new L2 table at offset 0 in the image, triggering an assertion in the qcow2 cache that would crash QEMU: qcow2_cache_entry_mark_dirty: Assertion `c->entries[i].offset !=3D 0' fai= led This patch adds an explicit check for this scenario and a new test case. Signed-off-by: Alberto Garcia Reviewed-by: Max Reitz Message-id: 92dac37191ae7844a2da22c122204eb493cc3133.1509718618.git.berto@i= galia.com Signed-off-by: Max Reitz --- block/qcow2-cluster.c | 8 ++++++++ tests/qemu-iotests/060 | 7 +++++++ tests/qemu-iotests/060.out | 6 ++++++ 3 files changed, 21 insertions(+) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index fb10e26068..2e072ed155 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -278,6 +278,14 @@ static int l2_allocate(BlockDriverState *bs, int l1_in= dex, uint64_t **table) goto fail; } =20 + /* If we're allocating the table at offset 0 then something is wrong */ + if (l2_offset =3D=3D 0) { + qcow2_signal_corruption(bs, true, -1, -1, "Preventing invalid " + "allocation of L2 table at offset 0"); + ret =3D -EIO; + goto fail; + } + ret =3D qcow2_cache_flush(bs, s->refcount_block_cache); if (ret < 0) { goto fail; diff --git a/tests/qemu-iotests/060 b/tests/qemu-iotests/060 index dead26aeaf..40f85cc216 100755 --- a/tests/qemu-iotests/060 +++ b/tests/qemu-iotests/060 @@ -253,6 +253,13 @@ poke_file "$TEST_IMG" "$rt_offset" "\x00\x00\x0= 0\x00\x00\x00\x00\x00" # causing a refcount block to be allocated at offset 0 $QEMU_IO -c "write 0 128k" "$TEST_IMG" | _filter_qemu_io =20 +echo +echo "=3D=3D=3D Testing empty refcount block =3D=3D=3D" +echo +_make_test_img 64M +poke_file "$TEST_IMG" "$rb_offset" "\x00\x00\x00\x00\x00\x00\x00\x0= 0" +$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io + # success, all done echo "*** done" rm -f $seq.full diff --git a/tests/qemu-iotests/060.out b/tests/qemu-iotests/060.out index 872719009c..5b8b518486 100644 --- a/tests/qemu-iotests/060.out +++ b/tests/qemu-iotests/060.out @@ -189,4 +189,10 @@ wrote 65536/65536 bytes at offset 0 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) qcow2: Marking image as corrupt: Preventing invalid allocation of refcount= block at offset 0; further corruption events will be suppressed write failed: Input/output error + +=3D=3D=3D Testing empty refcount block =3D=3D=3D + +Formatting 'TEST_DIR/t.IMGFMT', fmt=3DIMGFMT size=3D67108864 +qcow2: Marking image as corrupt: Preventing invalid allocation of L2 table= at offset 0; further corruption events will be suppressed +write failed: Input/output error *** done --=20 2.13.6