From nobody Mon Feb 9 03:13:12 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.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 Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1625570761314710.7595751938077; Tue, 6 Jul 2021 04:26:01 -0700 (PDT) Received: from localhost ([::1]:60346 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m0jDE-00068x-9F for importer@patchew.org; Tue, 06 Jul 2021 07:26:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60374) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m0jBW-0003Jk-4c for qemu-devel@nongnu.org; Tue, 06 Jul 2021 07:24:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:50709) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m0jBM-0000fs-NR for qemu-devel@nongnu.org; Tue, 06 Jul 2021 07:24:13 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-152-OibjECFeNvyem_PdF4ntJQ-1; Tue, 06 Jul 2021 07:24:03 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 41C59C740A; Tue, 6 Jul 2021 11:23:46 +0000 (UTC) Received: from merkur.redhat.com (ovpn-113-253.ams2.redhat.com [10.36.113.253]) by smtp.corp.redhat.com (Postfix) with ESMTP id 01B5660E3A; Tue, 6 Jul 2021 11:23:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625570644; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xmg7NdZ8n9UDUL99RDPfnI1r25/UyjiLO+BorYSDbps=; b=VKq9UZuGs2aFS4LGyBFzyRxvL95QJC1qqr1vf90qHdDOSW3Ty6+5nFKbpLXAr1IK/PTA4R z8agOGdnT3oMXdB1BPMkb9Y8nI3fBCG03si4glYsT+Qb6GbR+OKn46RFIIZj4YJBkysg3L ZbtI20AJoPVflcWPuKuE5mL5jWO2Dlg= X-MC-Unique: OibjECFeNvyem_PdF4ntJQ-1 From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PATCH v5 1/6] qcow2: Fix dangling pointer after reopen for 'file' Date: Tue, 6 Jul 2021 13:23:35 +0200 Message-Id: <20210706112340.223334-2-kwolf@redhat.com> In-Reply-To: <20210706112340.223334-1-kwolf@redhat.com> References: <20210706112340.223334-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.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; Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.442, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action 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: kwolf@redhat.com, vsementsov@virtuozzo.com, berto@igalia.com, qemu-devel@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1625570762328100001 Content-Type: text/plain; charset="utf-8" Without an external data file, s->data_file is a second pointer with the same value as bs->file. When changing bs->file to a different BdrvChild and freeing the old BdrvChild, s->data_file must also be updated, otherwise it points to freed memory and causes crashes. This problem was caught by iotests case 245. Fixes: df2b7086f169239ebad5d150efa29c9bb6d4f820 Signed-off-by: Kevin Wolf Reviewed-by: Vladimir Sementsov-Ogievskiy --- block/qcow2.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/block/qcow2.c b/block/qcow2.c index ee4530cdbd..cb459ef6a6 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -962,6 +962,7 @@ static bool read_cache_sizes(BlockDriverState *bs, Qemu= Opts *opts, } =20 typedef struct Qcow2ReopenState { + bool had_data_file; Qcow2Cache *l2_table_cache; Qcow2Cache *refcount_block_cache; int l2_slice_size; /* Number of entries in a slice of the L2 table */ @@ -1932,6 +1933,8 @@ static int qcow2_reopen_prepare(BDRVReopenState *stat= e, r =3D g_new0(Qcow2ReopenState, 1); state->opaque =3D r; =20 + r->had_data_file =3D has_data_file(state->bs); + ret =3D qcow2_update_options_prepare(state->bs, r, state->options, state->flags, errp); if (ret < 0) { @@ -1966,7 +1969,18 @@ fail: =20 static void qcow2_reopen_commit(BDRVReopenState *state) { + BDRVQcow2State *s =3D state->bs->opaque; + Qcow2ReopenState *r =3D state->opaque; + qcow2_update_options_commit(state->bs, state->opaque); + if (!r->had_data_file && s->data_file !=3D state->bs->file) { + /* + * If s->data_file is just a second pointer to bs->file (which is = the + * case without an external data file), it may need to be updated. + */ + s->data_file =3D state->bs->file; + assert(!has_data_file(state->bs)); + } g_free(state->opaque); } =20 --=20 2.31.1