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Fri, 4 Jun 2021 00:08:47 +0000 From: Damien Le Moal To: Colin Ian King CC: Alasdair Kergon , Mike Snitzer , "dm-devel@redhat.com" , "linux-kernel@vger.kernel.org" Subject: Re: dm: Forbid requeue of writes to zones Thread-Topic: dm: Forbid requeue of writes to zones Thread-Index: AQHXWMY2crVy6LmSRk+Dbf+Tih0t2g== Date: Fri, 4 Jun 2021 00:08:47 +0000 Message-ID: References: <7e7530a9-7939-2ad6-bfe1-d3aeeeed1f77@canonical.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: canonical.com; dkim=none (message not signed) header.d=none;canonical.com; dmarc=none action=none header.from=wdc.com; x-originating-ip: [2400:2411:43c0:6000:f9bc:fd30:41b8:96f2] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 49b71c6f-3832-4ec1-5b8c-08d926ececbe x-ms-traffictypediagnostic: DM6PR04MB5163: x-microsoft-antispam-prvs: wdcipoutbound: EOP-TRUE x-ms-oob-tlc-oobclassifiers: OLM:1388; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; 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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: DM6PR04MB7081.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 49b71c6f-3832-4ec1-5b8c-08d926ececbe X-MS-Exchange-CrossTenant-originalarrivaltime: 04 Jun 2021 00:08:47.4705 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: Tqm2tSZr4khb6BmC/T0NaBccCSVNRl0Q4VVvnpkLd3iI2B4lySV3kh0cabXHHBQbs1X6m/Vk+gLTK7e8iBSaFg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR04MB5163 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/06/04 7:17, Colin Ian King wrote:=0A= > Hi,=0A= > =0A= > Static analysis with Coverity on Linux next has found and issue in=0A= > drivers/md/dm.c with the following commit:=0A= > =0A= > commit 2c243153d1d4be4e23735cd10984ac17c7a54531=0A= > Author: Damien Le Moal =0A= > Date: Wed May 26 06:24:58 2021 +0900=0A= > =0A= > dm: Forbid requeue of writes to zones=0A= > =0A= > The analysis is as follows:=0A= > =0A= > 828 static void dec_pending(struct dm_io *io, blk_status_t error)=0A= > 829 {=0A= > 830 unsigned long flags;=0A= > 831 blk_status_t io_error;=0A= > =0A= > 1. var_decl: Declaring variable bio without initializer.=0A= =0A= This one is related to #7.=0A= =0A= > =0A= > 832 struct bio *bio;=0A= > 833 struct mapped_device *md =3D io->md;=0A= > 834=0A= > 835 /* Push-back supersedes any I/O errors */=0A= > =0A= > 2. Condition !!error, taking true branch.=0A= > =0A= > 836 if (unlikely(error)) {=0A= > 837 spin_lock_irqsave(&io->endio_lock, flags);=0A= > =0A= > 3. Condition io->status =3D=3D 11 /* (blk_status_t)11 */, taking fals= e=0A= > branch.=0A= > =0A= > 838 if (!(io->status =3D=3D BLK_STS_DM_REQUEUE &&=0A= > __noflush_suspending(md)))=0A= > 839 io->status =3D error;=0A= > 840 spin_unlock_irqrestore(&io->endio_lock, flags);=0A= > 841 }=0A= > 842=0A= =0A= My patch does not touch these hunks. They are as is. So that is not new.=0A= =0A= > =0A= > 4. Condition atomic_dec_and_test(&io->io_count), taking true branch.= =0A= > =0A= > 843 if (atomic_dec_and_test(&io->io_count)) {=0A= > =0A= > 5. Condition io->status =3D=3D 11 /* (blk_status_t)11 */, taking true= =0A= > branch.=0A= > =0A= > 844 if (io->status =3D=3D BLK_STS_DM_REQUEUE) {=0A= > 845 /*=0A= > 846 * Target requested pushing back the I/O.=0A= > 847 */=0A= > 848 spin_lock_irqsave(&md->deferred_lock, flags);= =0A= > =0A= > 6. Condition __noflush_suspending(md), taking true branch.=0A= > =0A= > 849 if (__noflush_suspending(md) &&=0A= =0A= I do not understand this one, nor #4.=0A= =0A= > =0A= > Uninitialized pointer read=0A= > 7. uninit_use_in_call: Using uninitialized value bio when calling=0A= > dm_is_zone_write.=0A= > =0A= > 850 !WARN_ON_ONCE(dm_is_zone_write(md, bio)))= =0A= > 851 /* NOTE early return due to=0A= > BLK_STS_DM_REQUEUE below */=0A= > 852 bio_list_add_head(&md->deferred,=0A= > io->orig_bio);=0A= =0A= The kernel build robot signaled this one already. Will send an incremental = patch=0A= asap today.=0A= =0A= > =0A= > The pointer bio is not initialized and yet is being used in the call to= =0A= > function dm_is_zone_write where pointer bio is being accessed. I'm not=0A= > sure what the original intent was, but this looks incorrect.=0A= > =0A= > Colin=0A= > =0A= =0A= =0A= -- =0A= Damien Le Moal=0A= Western Digital Research=0A= 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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 5EA2DC47096 for ; Fri, 4 Jun 2021 00:09:13 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) (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 DDF396140A for ; Fri, 4 Jun 2021 00:09:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DDF396140A Authentication-Results: mail.kernel.org; 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Fri, 4 Jun 2021 00:08:47 +0000 From: Damien Le Moal To: Colin Ian King Thread-Topic: dm: Forbid requeue of writes to zones Thread-Index: AQHXWMY2crVy6LmSRk+Dbf+Tih0t2g== Date: Fri, 4 Jun 2021 00:08:47 +0000 Message-ID: References: <7e7530a9-7939-2ad6-bfe1-d3aeeeed1f77@canonical.com> Accept-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [2400:2411:43c0:6000:f9bc:fd30:41b8:96f2] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 49b71c6f-3832-4ec1-5b8c-08d926ececbe x-ms-traffictypediagnostic: DM6PR04MB5163: x-microsoft-antispam-prvs: wdcipoutbound: EOP-TRUE x-ms-oob-tlc-oobclassifiers: OLM:1388 x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0 x-microsoft-antispam-message-info: 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 x-forefront-antispam-report: CIP:255.255.255.255; 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Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-MIME-Autoconverted: from quoted-printable to 8bit by lists01.pubmisc.prod.ext.phx2.redhat.com id 15408vAw020761 X-loop: dm-devel@redhat.com Cc: "dm-devel@redhat.com" , Mike Snitzer , Alasdair Kergon , "linux-kernel@vger.kernel.org" Subject: Re: [dm-devel] dm: Forbid requeue of writes to zones X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On 2021/06/04 7:17, Colin Ian King wrote: > Hi, > > Static analysis with Coverity on Linux next has found and issue in > drivers/md/dm.c with the following commit: > > commit 2c243153d1d4be4e23735cd10984ac17c7a54531 > Author: Damien Le Moal > Date: Wed May 26 06:24:58 2021 +0900 > > dm: Forbid requeue of writes to zones > > The analysis is as follows: > > 828 static void dec_pending(struct dm_io *io, blk_status_t error) > 829 { > 830 unsigned long flags; > 831 blk_status_t io_error; > > 1. var_decl: Declaring variable bio without initializer. This one is related to #7. > > 832 struct bio *bio; > 833 struct mapped_device *md = io->md; > 834 > 835 /* Push-back supersedes any I/O errors */ > > 2. Condition !!error, taking true branch. > > 836 if (unlikely(error)) { > 837 spin_lock_irqsave(&io->endio_lock, flags); > > 3. Condition io->status == 11 /* (blk_status_t)11 */, taking false > branch. > > 838 if (!(io->status == BLK_STS_DM_REQUEUE && > __noflush_suspending(md))) > 839 io->status = error; > 840 spin_unlock_irqrestore(&io->endio_lock, flags); > 841 } > 842 My patch does not touch these hunks. They are as is. So that is not new. > > 4. Condition atomic_dec_and_test(&io->io_count), taking true branch. > > 843 if (atomic_dec_and_test(&io->io_count)) { > > 5. Condition io->status == 11 /* (blk_status_t)11 */, taking true > branch. > > 844 if (io->status == BLK_STS_DM_REQUEUE) { > 845 /* > 846 * Target requested pushing back the I/O. > 847 */ > 848 spin_lock_irqsave(&md->deferred_lock, flags); > > 6. Condition __noflush_suspending(md), taking true branch. > > 849 if (__noflush_suspending(md) && I do not understand this one, nor #4. > > Uninitialized pointer read > 7. uninit_use_in_call: Using uninitialized value bio when calling > dm_is_zone_write. > > 850 !WARN_ON_ONCE(dm_is_zone_write(md, bio))) > 851 /* NOTE early return due to > BLK_STS_DM_REQUEUE below */ > 852 bio_list_add_head(&md->deferred, > io->orig_bio); The kernel build robot signaled this one already. Will send an incremental patch asap today. > > The pointer bio is not initialized and yet is being used in the call to > function dm_is_zone_write where pointer bio is being accessed. I'm not > sure what the original intent was, but this looks incorrect. > > Colin > -- Damien Le Moal Western Digital Research -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel