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=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS 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 84334C352A4 for ; Mon, 10 Feb 2020 00:38:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A0D42464E for ; Mon, 10 Feb 2020 00:38:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=wdc.com header.i=@wdc.com header.b="QicvxkAE"; dkim=pass (1024-bit key) header.d=sharedspace.onmicrosoft.com header.i=@sharedspace.onmicrosoft.com header.b="kUs12wux" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727045AbgBJAiv (ORCPT ); Sun, 9 Feb 2020 19:38:51 -0500 Received: from esa1.hgst.iphmx.com ([68.232.141.245]:8598 "EHLO esa1.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726961AbgBJAiv (ORCPT ); Sun, 9 Feb 2020 19:38:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=wdc.com; i=@wdc.com; q=dns/txt; s=dkim.wdc.com; t=1581295130; x=1612831130; h=from:to:cc:subject:date:message-id:references: content-transfer-encoding:mime-version; bh=t5XHYJaBMoQR9qV2HXO0EWI2TrzcW2Q7VfF5TgWBZU8=; b=QicvxkAEigvvp4zKiLIj+A5zx1c2/2w9mKPzL4wy1JNboXnfiR1wWQJ+ Su3dagIbM28RFpCuJVNaWoaaw5Qy8LxLhv9exIZnr7gcV7PBm/867CB07 oI6YHJwXqQStM4Mvkvk9kSDz6JfG3VOFsoFpPKS2VH4iTvGLDJM5mzqnR YVH5OKYFgu+SHJlT7c3SzfJY5tCvhMrVn+VaR5VAcPdNB6RP3bqM7HH5J Te9i4TU/+wtrzVp58Ppkg4W/m+1fDp7aZ30NFjbafVnxAcB0b7oelOJOB ZgUJ4i9OU3CjMQAFl1nE4dsuB6DK/6nJIpi9GU3hsuAtxswLKKkQzMITY Q==; IronPort-SDR: pn5ety1LfOAQkE8hW5nWELbikQAJYf4mhzjtJr4jC4to3TwkpnmCeAqe1vppTgPutlZtnYgYjg /zMKCqg0TDZLrpoHV5CbIXXM2cEW/RTPxa6l2Xn6IonKFWtKOmFIVB7Pdjklrya1Dp4f4Yhn/H 0PlI0JyfvI9LioDIxBnNXAcO9/8TxI7EaTnOp+YyT+r+z5YHMRm1Yhj2in8kylz95uM/pzxbL/ VXNwQcv9NNzs5Ykz1pJFa7QHXk3TnmmaTUFpGM/Wso/rEFM0KkGWkP0EyfLNj8x32ko16TBhc8 edM= X-IronPort-AV: E=Sophos;i="5.70,423,1574092800"; d="scan'208";a="237466878" Received: from mail-dm6nam10lp2101.outbound.protection.outlook.com (HELO NAM10-DM6-obe.outbound.protection.outlook.com) ([104.47.58.101]) by ob1.hgst.iphmx.com with ESMTP; 10 Feb 2020 08:38:49 +0800 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=XPJWkLh835ze2rkEbjp+wmIxMmlMPEwZ6QGdT4wc5PT2bn0HiVbK74ZeRbLLfiVpFY1S0i7XnFNQK+02biddFvm5mWuLkDmOAhY9EEU5Lya9BMU4v8TLbbTEv5a1YdOR5WmnkAMsOnzdpt7mwV4ISRyFm35KlURdvkVr2Inz8pIZHVWwNlNEoyH1uOFxxuBKqcqvq+s8nSpVMlbxASCc+4mWDWnnZUQ/n2vcHSEeHQYrCVY/+PzwixtsZKajZcELwSlo6/JZ4ju6dlH0/QltjBjiEhESK5gLMl0Oktnidj5RVZ+QXoye4kK3coFsPWxdZ01TwEFmY0B4m15n5M58Iw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=t5XHYJaBMoQR9qV2HXO0EWI2TrzcW2Q7VfF5TgWBZU8=; b=DHPVs4Y7QZPZjP74rCYRwBIdabeKURfCw4pvLPuO2CP2cszoHvHfrfyOP6Qfz8TsCJlTvMzpToLxHK/YRriPAxyMRMbC3H6jIfBZcPcXMs08DIKobAVqgLLHemfKI3Wrv3o/cYlDXOFV6oul0pg/ITWKVbOQaFzIY79FG4LIOF+S6/flsS7OQ8euaWt16jsA35/8muWpV91uLtwcrDCVJH2cSg0/0m8dWC3xld9epmpR+H4zrWgAL6tn2cqkimCwHSUQdiHGiUrGYlgim8EHCBuyVjScboT5JmEa/huHw7UynXUvQDDTRfvaj+NCOlSNHX+EWPw3NdEehTMd2U6qAg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=wdc.com; dmarc=pass action=none header.from=wdc.com; dkim=pass header.d=wdc.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sharedspace.onmicrosoft.com; s=selector2-sharedspace-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=t5XHYJaBMoQR9qV2HXO0EWI2TrzcW2Q7VfF5TgWBZU8=; b=kUs12wuxxTdrx6VeT+7ErA0pLahssU2ludfQga6jlXlcUylcPJSs/cb0fbWJaqHrOFE0l0DHOdpr0BoWWTwRWIRKxnMneoGynbl535qbMoP3jDvvgSq28W+WM5oi5ukNIwjWQQ1h3ZpfNsXJ0KzcTgy861wSAmlxAk+V33JZrMs= Received: from BYAPR04MB5749.namprd04.prod.outlook.com (20.179.57.21) by BYAPR04MB3800.namprd04.prod.outlook.com (52.135.214.148) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2707.24; Mon, 10 Feb 2020 00:38:48 +0000 Received: from BYAPR04MB5749.namprd04.prod.outlook.com ([fe80::a8ea:4ba9:cb57:e90f]) by BYAPR04MB5749.namprd04.prod.outlook.com ([fe80::a8ea:4ba9:cb57:e90f%5]) with mapi id 15.20.2707.028; Mon, 10 Feb 2020 00:38:48 +0000 From: Chaitanya Kulkarni To: Jan Kara , Jens Axboe CC: "linux-block@vger.kernel.org" , "tristmd@gmail.com" , "stable@vger.kernel.org" Subject: Re: [PATCH] blktrace: Protect q->blk_trace with RCU Thread-Topic: [PATCH] blktrace: Protect q->blk_trace with RCU Thread-Index: AQHV3Pm1sBn7cXCscUyQVcxbWOqGBg== Date: Mon, 10 Feb 2020 00:38:47 +0000 Message-ID: References: <20200206142812.25989-1-jack@suse.cz> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Chaitanya.Kulkarni@wdc.com; x-originating-ip: [199.255.45.62] x-ms-publictraffictype: Email x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 8d83e281-6dfd-47d6-130c-08d7adc197b4 x-ms-traffictypediagnostic: BYAPR04MB3800: x-microsoft-antispam-prvs: wdcipoutbound: EOP-TRUE x-ms-oob-tlc-oobclassifiers: OLM:949; x-forefront-prvs: 03094A4065 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(4636009)(366004)(136003)(39850400004)(396003)(346002)(376002)(199004)(189003)(86362001)(33656002)(5660300002)(54906003)(316002)(71200400001)(66946007)(55016002)(53546011)(64756008)(66446008)(6506007)(66476007)(66556008)(9686003)(52536014)(76116006)(8936002)(2906002)(81156014)(4326008)(8676002)(81166006)(7696005)(478600001)(110136005)(26005)(186003);DIR:OUT;SFP:1102;SCL:1;SRVR:BYAPR04MB3800;H:BYAPR04MB5749.namprd04.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: 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 x-ms-exchange-antispam-messagedata: RcPY6JyzgKnvzmirxcfanN6/VxE89vboYhmeBon2ut2ADs+Vb9ahehMcLV7M2AUZDMpLmlNrLjupygnfbCXi7TyVWQLZB9PHo9lKtXj1KlKdLbURjsDODtUNfQ7oy4/sbMGweiDmS+WQwFdY59C0rQ== x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8d83e281-6dfd-47d6-130c-08d7adc197b4 X-MS-Exchange-CrossTenant-originalarrivaltime: 10 Feb 2020 00:38:47.9280 (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: ZkgKB0HZNsJQ+7/AMAmv1iBQTFOW5ym2wdsfzdQ1y44jZULyQUPx4yyTmp+IUX7LnzFkOJu8A84SSYXFavR90rfuKIRtfu7x2LPpiHkHIPg= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR04MB3800 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Looks good.=0A= =0A= Reviewed-by: Chaitanya Kulkarni =0A= =0A= On 02/06/2020 06:28 AM, Jan Kara wrote:=0A= > KASAN is reporting that __blk_add_trace() has a use-after-free issue=0A= > when accessing q->blk_trace. Indeed the switching of block tracing (and= =0A= > thus eventual freeing of q->blk_trace) is completely unsynchronized with= =0A= > the currently running tracing and thus it can happen that the blk_trace= =0A= > structure is being freed just while __blk_add_trace() works on it.=0A= > Protect accesses to q->blk_trace by RCU during tracing and make sure we= =0A= > wait for the end of RCU grace period when shutting down tracing. Luckily= =0A= > that is rare enough event that we can afford that. Note that postponing= =0A= > the freeing of blk_trace to an RCU callback should better be avoided as= =0A= > it could have unexpected user visible side-effects as debugfs files=0A= > would be still existing for a short while block tracing has been shut=0A= > down.=0A= >=0A= > Link:https://bugzilla.kernel.org/show_bug.cgi?id=3D205711=0A= > CC:stable@vger.kernel.org=0A= > Reported-by: Tristan=0A= > Signed-off-by: Jan Kara=0A= =0A=