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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2AF52C00140 for ; Wed, 24 Aug 2022 09:59:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231846AbiHXJ7r (ORCPT ); Wed, 24 Aug 2022 05:59:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236289AbiHXJ7q (ORCPT ); Wed, 24 Aug 2022 05:59:46 -0400 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B3407A519; Wed, 24 Aug 2022 02:59:43 -0700 (PDT) Received: from pps.filterd (m0127361.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 27O9WFJq035230; Wed, 24 Aug 2022 09:59:42 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=pp1; bh=wNN/FM1pslClq4PA/Vw/Ikr2p+6VyIzMoVg3UFHtxuc=; b=CQUmVIOMoTf9R6uN9RGaT4JX8h63ZNJX3NBAzV4Np9vblqLm+iA+Mx9XzabMs2qG//aC HkvAFYNUDuQ9P+DzqHJDHftf9tTo++uvx+BmOi0d+l8shAGQRxledLjD6k3bEcrrqZRY OyecI87xpZVLXnStoWnRBWFcVJzAz5IhHSqotujZ79/S0wKZjXpjITtEkN1lXGC3aPvI +CCM+ZTyykwAfk7qN8Qoo8aLX2EiEVXVBxjH6l0IuAL6iDbH8zjcYsdfhrOgA3ssY9xm BsUyoB7LBhpXxv9dLD5IWjr5uNa0/XNq6RMjUGmAYQdryQ1yCmmlNIfdwMR+ClK9GVS3 Eg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3j5hedgvpa-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 24 Aug 2022 09:59:42 +0000 Received: from m0127361.ppops.net (m0127361.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 27O9Zs5T006799; Wed, 24 Aug 2022 09:59:42 GMT Received: from ppma02fra.de.ibm.com (47.49.7a9f.ip4.static.sl-reverse.com [159.122.73.71]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3j5hedgvnh-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 24 Aug 2022 09:59:42 +0000 Received: from pps.filterd (ppma02fra.de.ibm.com [127.0.0.1]) by ppma02fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 27O9okl8016026; Wed, 24 Aug 2022 09:59:40 GMT Received: from b06cxnps4074.portsmouth.uk.ibm.com (d06relay11.portsmouth.uk.ibm.com [9.149.109.196]) by ppma02fra.de.ibm.com with ESMTP id 3j2q88umgt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 24 Aug 2022 09:59:40 +0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 27O9xYb330015804 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 24 Aug 2022 09:59:34 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BF3FC4C040; Wed, 24 Aug 2022 09:59:34 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6A5894C044; Wed, 24 Aug 2022 09:59:34 +0000 (GMT) Received: from localhost (unknown [9.171.51.29]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Wed, 24 Aug 2022 09:59:34 +0000 (GMT) Date: Wed, 24 Aug 2022 11:59:32 +0200 From: Vasily Gorbik To: Brian Foster , Heiko Carstens Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, geraldsc@de.ibm.com Subject: Re: [PATCH] s390: fix double free of GS and RI CBs on fork() failure Message-ID: References: <20220816155407.537372-1-bfoster@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-GUID: rVHBxEW5pgclDN5D3gI5N2knT1doseyY X-Proofpoint-ORIG-GUID: O8YZxl3kp01fY_NXVl5X6SN8yKRtLfZc X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-08-24_05,2022-08-22_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=0 spamscore=0 clxscore=1015 mlxscore=0 lowpriorityscore=0 bulkscore=0 phishscore=0 malwarescore=0 impostorscore=0 mlxlogscore=974 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2207270000 definitions=main-2208240036 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Wed, Aug 24, 2022 at 10:01:00AM +0200, Heiko Carstens wrote: > On Tue, Aug 16, 2022 at 11:54:07AM -0400, Brian Foster wrote: > > The pointers for guarded storage and runtime instrumentation control > > blocks are stored in the thread_struct of the associated task. These > > pointers are initially copied on fork() via arch_dup_task_struct() > > and then cleared via copy_thread() before fork() returns. If fork() > > happens to fail after the initial task dup and before copy_thread(), > > the newly allocated task and associated thread_struct memory are > > freed via free_task() -> arch_release_task_struct(). This results in > > a double free of the guarded storage and runtime info structs > > because the fields in the failed task still refer to memory > > associated with the source task. > > > > This problem can manifest as a BUG_ON() in set_freepointer() (with > > CONFIG_SLAB_FREELIST_HARDENED enabled) or KASAN splat (if enabled) > > when running trinity syscall fuzz tests on s390x. To avoid this > > problem, clear the associated pointer fields in > > arch_dup_task_struct() immediately after the new task is copied. > > Note that the RI flag is still cleared in copy_thread() because it > > resides in thread stack memory and that is where stack info is > > copied. > > > > Signed-off-by: Brian Foster > > --- > > arch/s390/kernel/process.c | 22 ++++++++++++++++------ > > 1 file changed, 16 insertions(+), 6 deletions(-) > > Reviewed-by: Heiko Carstens > > Thanks for debugging and fixing this! > > Vasily, could you pick this one up, and also add the Fixes: and Cc: > stable tags as proposed by Gerald? > Thanks! Applied, Thank you!