From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 24 Sep 2018 13:41:30 +0200 (CEST) Received: from mail.linuxfoundation.org ([140.211.169.12]:41514 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S23994243AbeIXLlXvpbQU (ORCPT ); Mon, 24 Sep 2018 13:41:23 +0200 Received: from localhost (ip-213-127-77-73.ip.prioritytelecom.net [213.127.77.73]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id EB12B1073; Mon, 24 Sep 2018 11:41:13 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guenter Roeck , Stafford Horne , Oleg Nesterov , Ralf Baechle , linux-mips@linux-mips.org, Jonas Bonn , Stefan Kristiansson , openrisc@lists.librecores.org, Jamie Iles , Thomas Gleixner , Vegard Nossum , Linus Torvalds , Amit Pundir Subject: [PATCH 3.18 036/105] kthread: fix boot hang (regression) on MIPS/OpenRISC Date: Mon, 24 Sep 2018 13:33:22 +0200 Message-Id: <20180924113117.566426729@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20180924113113.268650190@linuxfoundation.org> References: <20180924113113.268650190@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 66522 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: gregkh@linuxfoundation.org Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vegard Nossum commit b0f5a8f32e8bbdaae1abb8abe2d3cbafaba57e08 upstream. This fixes a regression in commit 4d6501dce079 where I didn't notice that MIPS and OpenRISC were reinitialising p->{set,clear}_child_tid to NULL after our initialisation in copy_process(). We can simply get rid of the arch-specific initialisation here since it is now always done in copy_process() before hitting copy_thread{,_tls}(). Review notes: - As far as I can tell, copy_process() is the only user of copy_thread_tls(), which is the only caller of copy_thread() for architectures that don't implement copy_thread_tls(). - After this patch, there is no arch-specific code touching p->set_child_tid or p->clear_child_tid whatsoever. - It may look like MIPS/OpenRISC wanted to always have these fields be NULL, but that's not true, as copy_process() would unconditionally set them again _after_ calling copy_thread_tls() before commit 4d6501dce079. Fixes: 4d6501dce079c1eb6bf0b1d8f528a5e81770109e ("kthread: Fix use-after-free if kthread fork fails") Reported-by: Guenter Roeck Tested-by: Guenter Roeck # MIPS only Acked-by: Stafford Horne Acked-by: Oleg Nesterov Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: Jonas Bonn Cc: Stefan Kristiansson Cc: openrisc@lists.librecores.org Cc: Jamie Iles Cc: Thomas Gleixner Signed-off-by: Vegard Nossum Signed-off-by: Linus Torvalds Signed-off-by: Amit Pundir Signed-off-by: Greg Kroah-Hartman --- arch/mips/kernel/process.c | 1 - arch/openrisc/kernel/process.c | 2 -- 2 files changed, 3 deletions(-) --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -87,7 +87,6 @@ int copy_thread(unsigned long clone_flag struct thread_info *ti = task_thread_info(p); struct pt_regs *childregs, *regs = current_pt_regs(); unsigned long childksp; - p->set_child_tid = p->clear_child_tid = NULL; childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; --- a/arch/openrisc/kernel/process.c +++ b/arch/openrisc/kernel/process.c @@ -152,8 +152,6 @@ copy_thread(unsigned long clone_flags, u top_of_kernel_stack = sp; - p->set_child_tid = p->clear_child_tid = NULL; - /* Locate userspace context on stack... */ sp -= STACK_FRAME_OVERHEAD; /* redzone */ sp -= sizeof(struct pt_regs);