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=-6.7 required=3.0 tests=FORGED_MUA_MOZILLA, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MSGID_FROM_MTA_HEADER,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 499DDC43332 for ; Fri, 20 Mar 2020 20:26:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1F8362072C for ; Fri, 20 Mar 2020 20:26:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727297AbgCTU0L (ORCPT ); Fri, 20 Mar 2020 16:26:11 -0400 Received: from mail-oln040092074016.outbound.protection.outlook.com ([40.92.74.16]:49318 "EHLO EUR04-DB3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727039AbgCTU0K (ORCPT ); Fri, 20 Mar 2020 16:26:10 -0400 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=HXFAKSLabCIOX+5xYo2zE6xLUwGcoOJNulJjj4rtqABS1bb+jbJrS2Hvf7aW/1sMz9LLILXH2W1nd+vXhKMcGOdU0VfWjd8wVkiSIB0ipXwq8GCDPhPANg+i3gbbkUgphCo5rIWgI9LRPoaPp5oyTR91TmMhmlRm8bf4HcRcMHeoAX1vyo1178nQn9zq/r/9cKkKwuy+CftKCjc3UvuJbNk8MZTvxWkmEOlrfjbrgQhSE51pJDpG/q0pr371B/l0pjWoG9FjiN7K9UwvgXFY0jPD/BAcDPHk8rtO/IdPIoEQdR6smi0F5+YmGabJDfsjbqXuNnqL61Esb/E8/wdb4Q== 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=1JfbhkBSgZXazwyxseEyQAUC1YhAoQp5Oog8RUXPNFw=; b=a4LZFo1iywMavDzd2QpM0phSwtpCfXnXOqSrZ/zcmIulOgVgjub9LR+pJvwz3hnAWwe5JsX4WYRl5+0wDCHHnK9qXl+TOKSIx01JdNVSVBB98WXaWm+EjKlLj2jYQviFTgUYIGQ9Xo11S0bgmUFgY7lTCUaZYy/q2jwbHRHZNu9E70I5SmGDeeFYKcpqc/9GdBQZuoNInrJElm+GSI11FU6K9HOHJBGrbFYt0OkSx0bhfvYFgA/HSNqw64RpLnNF8WfR7HfTYxcz7EWcGhscZ+gd5w8LpOIoFgdm6CIuHj90UT6hyD8BwI63JQ4RyHhLP27z15GHLCkjwacZpqn+0g== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=hotmail.de; dmarc=pass action=none header.from=hotmail.de; dkim=pass header.d=hotmail.de; arc=none Received: from DB3EUR04FT027.eop-eur04.prod.protection.outlook.com (2a01:111:e400:7e0c::35) by DB3EUR04HT196.eop-eur04.prod.protection.outlook.com (2a01:111:e400:7e0c::385) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2814.13; Fri, 20 Mar 2020 20:26:07 +0000 Received: from AM6PR03MB5170.eurprd03.prod.outlook.com (10.152.24.52) by DB3EUR04FT027.mail.protection.outlook.com (10.152.24.122) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2814.13 via Frontend Transport; Fri, 20 Mar 2020 20:26:07 +0000 X-IncomingTopHeaderMarker: OriginalChecksum:5140F074D3BA6EE72F72325EBF172E17A127F04B477E75084089DA1CF3B5176F;UpperCasedChecksum:5AA8F7F66C1A49E3636C4506443A487E85E327A921737B7C5C282F12946CA642;SizeAsReceived:9390;Count:49 Received: from AM6PR03MB5170.eurprd03.prod.outlook.com ([fe80::1956:d274:cab3:b4dd]) by AM6PR03MB5170.eurprd03.prod.outlook.com ([fe80::1956:d274:cab3:b4dd%6]) with mapi id 15.20.2835.017; Fri, 20 Mar 2020 20:26:07 +0000 From: Bernd Edlinger Subject: [PATCH v6 06/16] exec: Fix a deadlock in strace To: Greg Kroah-Hartman , Kirill Tkhai , "Eric W. Biederman" , Christian Brauner , Kees Cook , Jann Horn , Jonathan Corbet , Alexander Viro , Andrew Morton , Alexey Dobriyan , Thomas Gleixner , Oleg Nesterov , Frederic Weisbecker , Andrei Vagin , Ingo Molnar , "Peter Zijlstra (Intel)" , Yuyang Du , David Hildenbrand , Sebastian Andrzej Siewior , Anshuman Khandual , David Howells , James Morris , Shakeel Butt , Jason Gunthorpe , Christian Kellner , Andrea Arcangeli , Aleksa Sarai , "Dmitry V. Levin" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "stable@vger.kernel.org" , "linux-api@vger.kernel.org" References: <077b63b7-6f5e-aa8e-bf96-a586b481cc46@hotmail.de> Message-ID: Date: Fri, 20 Mar 2020 21:26:04 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 In-Reply-To: <077b63b7-6f5e-aa8e-bf96-a586b481cc46@hotmail.de> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR2P281CA0030.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:14::17) To AM6PR03MB5170.eurprd03.prod.outlook.com (2603:10a6:20b:ca::23) X-Microsoft-Original-Message-ID: <4512747c-4434-6bc3-f1c3-4476b5d9c341@hotmail.de> MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.1.101] (92.77.140.102) by FR2P281CA0030.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:14::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2835.18 via Frontend Transport; Fri, 20 Mar 2020 20:26:05 +0000 X-Microsoft-Original-Message-ID: <4512747c-4434-6bc3-f1c3-4476b5d9c341@hotmail.de> X-TMN: [GK3/1T/vuH3xlYbWn/t43WvJuwsfTCp8] X-MS-PublicTrafficType: Email X-IncomingHeaderCount: 49 X-EOPAttributedMessage: 0 X-MS-Office365-Filtering-Correlation-Id: e6fc08d2-3159-4c8c-166e-08d7cd0ceb7e X-MS-TrafficTypeDiagnostic: DB3EUR04HT196: X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 13bkMFgKhwMHXmp/MgPMzW0+Sf6BXH7rx8M+TAdU7ZShxGvgx9YOlxJSY5yhN5407o1qNr//PIm30YwrYcGBu9UnldjR2vhYjiMCP9TN2TOp07k68ZcJ4eMgPgTqIMuDtpe+AtXMqrpsUXh8FmrJ88+QKv0bak5JQq07iARvXWkMZzdu6mEfQXBS5ihdJxix8ea3LowKd0CFTHA1SfI0c41b6LeBeunIj9jRiGfNrww= X-MS-Exchange-AntiSpam-MessageData: jrODIZyMol/kLrqjf7M+F+AALMj102wpttvwXaKQYZNbSfdjnMTLyF53EmPY8XdR7FB6CmrNaVaXaeosO26s9OYtNsJZtrWDEPmlwaPVK4wLHBaTYi4HYSJbjwwCpU7tem5aK32ZBKQdvkeimZqo9w== X-OriginatorOrg: outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: e6fc08d2-3159-4c8c-166e-08d7cd0ceb7e X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Mar 2020 20:26:07.3353 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa X-MS-Exchange-CrossTenant-FromEntityHeader: Internet X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB3EUR04HT196 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This fixes a deadlock in the tracer when tracing a multi-threaded application that calls execve while more than one thread are running. I observed that when running strace on the gcc test suite, it always blocks after a while, when expect calls execve, because other threads have to be terminated. They send ptrace events, but the strace is no longer able to respond, since it is blocked in vm_access. The deadlock is always happening when strace needs to access the tracees process mmap, while another thread in the tracee starts to execve a child process, but that cannot continue until the PTRACE_EVENT_EXIT is handled and the WIFEXITED event is received: strace D 0 30614 30584 0x00000000 Call Trace: __schedule+0x3ce/0x6e0 schedule+0x5c/0xd0 schedule_preempt_disabled+0x15/0x20 __mutex_lock.isra.13+0x1ec/0x520 __mutex_lock_killable_slowpath+0x13/0x20 mutex_lock_killable+0x28/0x30 mm_access+0x27/0xa0 process_vm_rw_core.isra.3+0xff/0x550 process_vm_rw+0xdd/0xf0 __x64_sys_process_vm_readv+0x31/0x40 do_syscall_64+0x64/0x220 entry_SYSCALL_64_after_hwframe+0x44/0xa9 expect D 0 31933 30876 0x80004003 Call Trace: __schedule+0x3ce/0x6e0 schedule+0x5c/0xd0 flush_old_exec+0xc4/0x770 load_elf_binary+0x35a/0x16c0 search_binary_handler+0x97/0x1d0 __do_execve_file.isra.40+0x5d4/0x8a0 __x64_sys_execve+0x49/0x60 do_syscall_64+0x64/0x220 entry_SYSCALL_64_after_hwframe+0x44/0xa9 This changes mm_access to use the new exec_update_mutex instead of cred_guard_mutex. This patch is based on the following patch by Eric W. Biederman: "[PATCH 0/5] Infrastructure to allow fixing exec deadlocks" Link: https://lore.kernel.org/lkml/87v9ne5y4y.fsf_-_@x220.int.ebiederm.org/ Signed-off-by: Bernd Edlinger Reviewed-by: Kees Cook --- kernel/fork.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index 036b692..e23ccac 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1224,7 +1224,7 @@ struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) struct mm_struct *mm; int err; - err = mutex_lock_killable(&task->signal->cred_guard_mutex); + err = mutex_lock_killable(&task->signal->exec_update_mutex); if (err) return ERR_PTR(err); @@ -1234,7 +1234,7 @@ struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) mmput(mm); mm = ERR_PTR(-EACCES); } - mutex_unlock(&task->signal->cred_guard_mutex); + mutex_unlock(&task->signal->exec_update_mutex); return mm; } -- 1.9.1