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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 490B6C43441 for ; Thu, 22 Nov 2018 02:16:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 183942075B for ; Thu, 22 Nov 2018 02:16:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 183942075B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732769AbeKVMyA (ORCPT ); Thu, 22 Nov 2018 07:54:00 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:51302 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732695AbeKVMyA (ORCPT ); Thu, 22 Nov 2018 07:54:00 -0500 Received: from localhost.localdomain (c-24-6-170-16.hsd1.ca.comcast.net [24.6.170.16]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 80A175B1; Thu, 22 Nov 2018 02:16:51 +0000 (UTC) Date: Wed, 21 Nov 2018 18:16:50 -0800 From: Andrew Morton To: Andrei Vagin Cc: Oleg Nesterov , linux-kernel@vger.kernel.org, "Eric W. Biederman" Subject: Re: [PATCH] ptrace: take into account saved_sigmask in PTRACE_{GET,SET}SIGMASK Message-Id: <20181121181650.8d2d6abcf83b9defb7195cd3@linux-foundation.org> In-Reply-To: <20181120060616.6043-1-avagin@gmail.com> References: <20181120060616.6043-1-avagin@gmail.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 19 Nov 2018 22:06:16 -0800 Andrei Vagin wrote: > There are a few system calls (pselect, ppoll, etc) which replace a task > sigmask while they are running in a kernel-space > > When a task calls one of these syscalls, the kernel saves a current > sigmask in task->saved_sigmask and sets a syscall sigmask. > > On syscall-exit-stop, ptrace traps a task before restoring the > saved_sigmask, so PTRACE_GETSIGMASK returns the syscall sigmask and > PTRACE_SETSIGMASK does nothing, because its sigmask is replaced by > saved_sigmask, when the task returns to user-space. > > This patch fixes this problem. PTRACE_GET_SIGMASK returns saved_sigmask > is it's set. PTRACE_SETSIGMASK drops the TIF_RESTORE_SIGMASK flag. Looks good to me, but what would I know. I'll await input from Eric and/or Oleg (please). > --- a/include/linux/sched/signal.h > +++ b/include/linux/sched/signal.h > @@ -417,10 +417,20 @@ static inline void set_restore_sigmask(void) > set_thread_flag(TIF_RESTORE_SIGMASK); > WARN_ON(!test_thread_flag(TIF_SIGPENDING)); > } > + > +static inline void clear_tsk_restore_sigmask(struct task_struct *tsk) > +{ > + clear_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK); > +} How irritating is it that this file uses "task" 85 times and "tsk" 19 times? What did that gain us? This patch worsens things. Oh well.