From patchwork Tue Apr 26 22:52:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 12828044 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 105AFC433F5 for ; Tue, 26 Apr 2022 22:53:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355940AbiDZW4O (ORCPT ); Tue, 26 Apr 2022 18:56:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355935AbiDZW4N (ORCPT ); Tue, 26 Apr 2022 18:56:13 -0400 Received: from out03.mta.xmission.com (out03.mta.xmission.com [166.70.13.233]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39A04473B2; Tue, 26 Apr 2022 15:53:05 -0700 (PDT) Received: from in02.mta.xmission.com ([166.70.13.52]:60022) by out03.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1njU3M-007FwD-9j; Tue, 26 Apr 2022 16:53:04 -0600 Received: from ip68-227-174-4.om.om.cox.net ([68.227.174.4]:35772 helo=localhost.localdomain) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1njU3L-006ASW-Aa; Tue, 26 Apr 2022 16:53:03 -0600 From: "Eric W. Biederman" To: linux-kernel@vger.kernel.org Cc: rjw@rjwysocki.net, Oleg Nesterov , mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, bigeasy@linutronix.de, Will Deacon , tj@kernel.org, linux-pm@vger.kernel.org, Peter Zijlstra , Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Chris Zankel , Max Filippov , inux-xtensa@linux-xtensa.org, Kees Cook , Jann Horn , "Eric W. Biederman" Date: Tue, 26 Apr 2022 17:52:09 -0500 Message-Id: <20220426225211.308418-7-ebiederm@xmission.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <878rrrh32q.fsf_-_@email.froward.int.ebiederm.org> References: <878rrrh32q.fsf_-_@email.froward.int.ebiederm.org> MIME-Version: 1.0 X-XM-SPF: eid=1njU3L-006ASW-Aa;;;mid=<20220426225211.308418-7-ebiederm@xmission.com>;;;hst=in02.mta.xmission.com;;;ip=68.227.174.4;;;frm=ebiederm@xmission.com;;;spf=softfail X-XM-AID: U2FsdGVkX196mjsOCd0SEDESfdGedhN7wA/hLrR7neg= X-SA-Exim-Connect-IP: 68.227.174.4 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [PATCH 7/9] ptrace: Simplify the wait_task_inactive call in ptrace_check_attach X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Asking wait_task_inactive to verify that tsk->__state == __TASK_TRACED was needed to detect the when ptrace_stop would decide not to stop after calling "set_special_state(TASK_TRACED)". With the recent cleanups ptrace_stop will always stop after calling set_special_state. Take advatnage of this by no longer asking wait_task_inactive to verify the state. If a bug is hit and wait_task_inactive does not succeed warn and return -ESRCH. Signed-off-by: "Eric W. Biederman" --- kernel/ptrace.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 16d1a84a2cae..0634da7ac685 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -265,17 +265,9 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state) } read_unlock(&tasklist_lock); - if (!ret && !ignore_state) { - if (!wait_task_inactive(child, __TASK_TRACED)) { - /* - * This can only happen if may_ptrace_stop() fails and - * ptrace_stop() changes ->state back to TASK_RUNNING, - * so we should not worry about leaking __TASK_TRACED. - */ - WARN_ON(READ_ONCE(child->__state) == __TASK_TRACED); - ret = -ESRCH; - } - } + if (!ret && !ignore_state && + WARN_ON_ONCE(!wait_task_inactive(child, 0))) + ret = -ESRCH; return ret; }