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 B8874C43334 for ; Fri, 3 Jun 2022 17:57:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345913AbiFCR5M (ORCPT ); Fri, 3 Jun 2022 13:57:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346528AbiFCRvP (ORCPT ); Fri, 3 Jun 2022 13:51:15 -0400 Received: from out01.mta.xmission.com (out01.mta.xmission.com [166.70.13.231]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B1C9656FAA for ; Fri, 3 Jun 2022 10:48:28 -0700 (PDT) Received: from in01.mta.xmission.com ([166.70.13.51]:36402) by out01.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1nxBPP-00Gg1P-0c; Fri, 03 Jun 2022 11:48:27 -0600 Received: from ip68-227-174-4.om.om.cox.net ([68.227.174.4]:42780 helo=email.froward.int.ebiederm.org.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1nxBPN-000zSt-Ka; Fri, 03 Jun 2022 11:48:26 -0600 From: "Eric W. Biederman" To: Linus Torvalds Cc: Date: Fri, 03 Jun 2022 12:48:19 -0500 Message-ID: <87v8th7i58.fsf@email.froward.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1nxBPN-000zSt-Ka;;;mid=<87v8th7i58.fsf@email.froward.int.ebiederm.org>;;;hst=in01.mta.xmission.com;;;ip=68.227.174.4;;;frm=ebiederm@xmission.com;;;spf=softfail X-XM-AID: U2FsdGVkX19mNLrrPBZ5vfWVQCM18ArZKaY0/4+5EE8= X-SA-Exim-Connect-IP: 68.227.174.4 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [GIT PULL] kthread cleanups for v5.19 X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This set of changes updates init and user mode helper tasks to be ordinary user mode tasks. In commit 40966e316f86 ("kthread: Ensure struct kthread is present for all kthreads") caused init and the user mode helper threads that call kernel_execve to have struct kthread allocated for them. This struct kthread going away during execve in turned made a use after free of struct kthread possible. The commit 343f4c49f243 ("kthread: Don't allocate kthread_struct for init and umh") is enough to fix the use after free and is simple enough to be backportable. The rest of the changes pass struct kernel_clone_args to clean things up and cause the code to make sense. In making init and the user mode helpers tasks purely user mode tasks I ran into two complications. The function task_tick_numa was detecting tasks without an mm by testing for the presence of PF_KTHREAD. The initramfs code in populate_initrd_image was using flush_delayed_fput to ensuere the closing of all it's file descriptors was complete, and flush_delayed_fput does not work in a userspace thread. I have looked and looked and more complications and in my code review I have not found any, and neither has anyone else with the code sitting in linux-next. Link: https://lkml.kernel.org/r/87mtfu4up3.fsf@email.froward.int.ebiederm.org Eric W. Biederman (8): kthread: Don't allocate kthread_struct for init and umh fork: Pass struct kernel_clone_args into copy_thread fork: Explicity test for idle tasks in copy_thread fork: Generalize PF_IO_WORKER handling init: Deal with the init process being a user mode process fork: Explicitly set PF_KTHREAD fork: Stop allowing kthreads to call execve sched: Update task_tick_numa to ignore tasks without an mm arch/alpha/kernel/process.c | 13 ++++++------ arch/arc/kernel/process.c | 13 ++++++------ arch/arm/kernel/process.c | 12 ++++++----- arch/arm64/kernel/process.c | 12 ++++++----- arch/csky/kernel/process.c | 15 ++++++------- arch/h8300/kernel/process.c | 10 ++++----- arch/hexagon/kernel/process.c | 12 ++++++----- arch/ia64/kernel/process.c | 15 +++++++------ arch/m68k/kernel/process.c | 12 ++++++----- arch/microblaze/kernel/process.c | 12 ++++++----- arch/mips/kernel/process.c | 13 ++++++------ arch/nios2/kernel/process.c | 12 ++++++----- arch/openrisc/kernel/process.c | 12 ++++++----- arch/parisc/kernel/process.c | 18 +++++++++------- arch/powerpc/kernel/process.c | 15 +++++++------ arch/riscv/kernel/process.c | 12 ++++++----- arch/s390/kernel/process.c | 12 ++++++----- arch/sh/kernel/process_32.c | 12 ++++++----- arch/sparc/kernel/process_32.c | 12 ++++++----- arch/sparc/kernel/process_64.c | 12 ++++++----- arch/um/kernel/process.c | 15 +++++++------ arch/x86/include/asm/fpu/sched.h | 2 +- arch/x86/include/asm/switch_to.h | 8 +++---- arch/x86/kernel/fpu/core.c | 4 ++-- arch/x86/kernel/process.c | 18 +++++++++------- arch/xtensa/kernel/process.c | 17 ++++++++------- fs/exec.c | 8 ++++--- include/linux/sched/task.h | 8 +++++-- init/initramfs.c | 2 ++ init/main.c | 2 +- kernel/fork.c | 46 +++++++++++++++++++++++++++++++++------- kernel/sched/fair.c | 2 +- kernel/umh.c | 6 +++--- 33 files changed, 234 insertions(+), 160 deletions(-) Signed-off-by: "Eric W. Biederman" p.s. My apologies for this coming in so late. The code has been ready just everyone in my house has been sick since the start of the merge window.