From nobody Tue Nov 4 15:43:11 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) 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=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1503967892487409.1767619670409; Mon, 28 Aug 2017 17:51:32 -0700 (PDT) Received: from localhost ([::1]:42087 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dmUkc-0007dt-KS for importer@patchew.org; Mon, 28 Aug 2017 20:51:30 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48544) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dmUCh-0001YY-Qp for qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:16:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dmUCe-0005oz-5j for qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:16:27 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:42402 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dmUCd-0005nj-Vf for qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:16:24 -0400 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v7T0EBJ8019642 for ; Mon, 28 Aug 2017 20:16:23 -0400 Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) by mx0b-001b2d01.pphosted.com with ESMTP id 2cmsfn2wme-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 28 Aug 2017 20:16:23 -0400 Received: from localhost by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Mon, 28 Aug 2017 18:16:21 -0600 Received: from b03ledav002.gho.boulder.ibm.com (b03ledav002.gho.boulder.ibm.com [9.17.130.233]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v7T0GKCL64880854; Mon, 28 Aug 2017 17:16:20 -0700 Received: from b03ledav002.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 98A3E136040; Mon, 28 Aug 2017 18:16:20 -0600 (MDT) Received: from localhost (unknown [9.80.85.217]) by b03ledav002.gho.boulder.ibm.com (Postfix) with ESMTP id 6588713603C; Mon, 28 Aug 2017 18:16:20 -0600 (MDT) From: Michael Roth To: qemu-devel@nongnu.org Date: Mon, 28 Aug 2017 19:14:32 -0500 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1503965694-10794-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1503965694-10794-1-git-send-email-mdroth@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17082900-0012-0000-0000-000014ECDC52 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007630; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000226; SDB=6.00909028; UDB=6.00455849; IPR=6.00689279; BA=6.00005557; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00016909; XFM=3.00000015; UTC=2017-08-29 00:16:22 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17082900-0013-0000-0000-00004F43FB4E Message-Id: <1503965694-10794-58-git-send-email-mdroth@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-08-28_13:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1708290001 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.158.5 Subject: [Qemu-devel] [PATCH 57/79] commit: Fix use after free in completion 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 , qemu-stable@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Kevin Wolf The final bdrv_set_backing_hd() could be working on already freed nodes because the commit job drops its references (through BlockBackends) to both overlay_bs and top already a bit earlier. One way to trigger the bug is hot unplugging a disk for which blockdev_mark_auto_del() cancels the block job. Fix this by taking BDS-level references while we're still using the nodes. Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf Reviewed-by: John Snow (cherry picked from commit 19ebd13ed45ad5d5f277f5914d55b83f13eb09eb) Signed-off-by: Michael Roth --- block/commit.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/block/commit.c b/block/commit.c index 76a0d98..3bae46e 100644 --- a/block/commit.c +++ b/block/commit.c @@ -89,6 +89,10 @@ static void commit_complete(BlockJob *job, void *opaque) int ret =3D data->ret; bool remove_commit_top_bs =3D false; =20 + /* Make sure overlay_bs and top stay around until bdrv_set_backing_hd(= ) */ + bdrv_ref(top); + bdrv_ref(overlay_bs); + /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before * the normal backing chain can be restored. */ blk_unref(s->base); @@ -124,6 +128,9 @@ static void commit_complete(BlockJob *job, void *opaque) if (remove_commit_top_bs) { bdrv_set_backing_hd(overlay_bs, top, &error_abort); } + + bdrv_unref(overlay_bs); + bdrv_unref(top); } =20 static void coroutine_fn commit_run(void *opaque) --=20 2.7.4