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=-17.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 23117C43214 for ; Wed, 18 Aug 2021 14:46:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0E5E0610CF for ; Wed, 18 Aug 2021 14:46:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239683AbhHROrR (ORCPT ); Wed, 18 Aug 2021 10:47:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54416 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239503AbhHROrH (ORCPT ); Wed, 18 Aug 2021 10:47:07 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DBEAC0613CF for ; Wed, 18 Aug 2021 07:46:33 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id m24-20020a17090a7f98b0290178b1a81700so2461577pjl.4 for ; Wed, 18 Aug 2021 07:46:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=qXzjfbGAZVCj6QW9wqbn9inaUOG8fQZNbV0kpPuNxx0=; b=Lu2O8omEZVQDTWjESwBuZ+lf1zjRjIByR6Cs9riuDZ3w+cgt769dUF7Zevnrfaeh3V 6SvlWSJTbDeoyOGtPIPJKSZhfYhv0qGij0lqO7H+5W9GOo6r4u9lSnOnIzaoS9NU/LDb x0RT1MxNKqjfJvtnKE6W3OptjH5RWYzwW6N1uO+4OqDc5P57P/e127DmlKop3dOQR6Hl Em5CkDOMsII/1VtxyY+6lUxKNXcFpI5WQsMuWYdREgL8/7TniSAYig45A3qGQMeVxgZu eYuh749M7iSpA6UBMZZkXpCEuF14BDq+NbURHFVaEGjxLMqR7ugt63k8KfXkIxi8l7z6 o3kw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=qXzjfbGAZVCj6QW9wqbn9inaUOG8fQZNbV0kpPuNxx0=; b=hST03Hlp31die1L59w0BR8CpkPnvRbKTVGSZYsZKW0u9b4NLweZKqZ9jsvaMZQrp6D fAUuvo4L3tqOhO2Bs11xsi3UOAJ9amAwCFcKppfMCzvaNDBM6PsRn49HccO/wpYoPxIE IJJpCc9vnXqjGGw7IHRp9xVtWyVCfm2UMIZLtPw+WQ64I0VzSPKrXWhqB5bcb4n25rCp J+49IUfPlSXO5hgxNLuo9xR49XE4Ga4EtgMlySxZBNg3mAAvEYdPvXEzwlGb/XGbBw5r atJS9wtt9Ks9hCM70dr7Xw1Zd9RJNWnlfZkLb6u/8O0VRhHz/L+UhhFXKhJvMWzQacTn vpDw== X-Gm-Message-State: AOAM532KQeM8x7lTMCr33w4YtQOQeOpPl0mtEpSxjHL2KYHsM2ALGjaB LpN21ew97kjtE/Wlc2Mdzzsafw== X-Google-Smtp-Source: ABdhPJylCghWDfRMk3LEy2Q0liijBW1FCSA7PeHn+t5IVu5O8IgcIWLjOrUuIVZ7233b08IzPXyPqg== X-Received: by 2002:a17:902:7282:b029:12c:75a0:faa5 with SMTP id d2-20020a1709027282b029012c75a0faa5mr7646785pll.35.1629297992628; Wed, 18 Aug 2021 07:46:32 -0700 (PDT) Received: from [192.168.1.116] ([66.219.217.159]) by smtp.gmail.com with ESMTPSA id y2sm130003pjl.6.2021.08.18.07.46.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Aug 2021 07:46:32 -0700 (PDT) Subject: Re: [PATCH] coredump: Limit what can interrupt coredumps To: Tony Battersby , Olivier Langlois , "Eric W. Biederman" , Oleg Nesterov Cc: Linus Torvalds , Linux Kernel Mailing List , linux-fsdevel , io-uring , Alexander Viro , "Pavel Begunkov>" References: <87y2bh4jg5.fsf@disp2133> <87sg1p4h0g.fsf_-_@disp2133> <20210614141032.GA13677@redhat.com> <87pmwmn5m0.fsf@disp2133> <4d93d0600e4a9590a48d320c5a7dd4c54d66f095.camel@trillion01.com> <8af373ec-9609-35a4-f185-f9bdc63d39b7@cybernetics.com> <9d194813-ecb1-2fe4-70aa-75faf4e144ad@kernel.dk> <0bc38b13-5a7e-8620-6dce-18731f15467e@kernel.dk> <24c795c6-4ec4-518e-bf9b-860207eee8c7@kernel.dk> <05c0cadc-029e-78af-795d-e09cf3e80087@cybernetics.com> <84640f18-79ee-d8e4-5204-41a2c2330ed8@kernel.dk> <3168284a-0b52-7845-07b1-a72bdfed915c@cybernetics.com> <16ded7e5-1f44-1c51-5759-35f835115665@cybernetics.com> From: Jens Axboe Message-ID: <90c35bf6-bf65-c997-1823-36c509cf72b1@kernel.dk> Date: Wed, 18 Aug 2021 08:46:30 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <16ded7e5-1f44-1c51-5759-35f835115665@cybernetics.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/18/21 8:37 AM, Tony Battersby wrote: > On 8/17/21 6:05 PM, Jens Axboe wrote: >> On 8/17/21 3:39 PM, Tony Battersby wrote: >>> On 8/17/21 5:28 PM, Jens Axboe wrote: >>>> Another approach - don't allow TWA_SIGNAL task_work to get queued if >>>> PF_SIGNALED has been set on the task. This is similar to how we reject >>>> task_work_add() on process exit, and the callers must be able to handle >>>> that already. >>>> >>>> Can you test this one on top of your 5.10-stable? >>>> >>>> >>>> diff --git a/fs/coredump.c b/fs/coredump.c >>>> index 07afb5ddb1c4..ca7c1ee44ada 100644 >>>> --- a/fs/coredump.c >>>> +++ b/fs/coredump.c >>>> @@ -602,6 +602,14 @@ void do_coredump(const kernel_siginfo_t *siginfo) >>>> .mm_flags = mm->flags, >>>> }; >>>> >>>> + /* >>>> + * task_work_add() will refuse to add work after PF_SIGNALED has >>>> + * been set, ensure that we flush any pending TIF_NOTIFY_SIGNAL work >>>> + * if any was queued before that. >>>> + */ >>>> + if (test_thread_flag(TIF_NOTIFY_SIGNAL)) >>>> + tracehook_notify_signal(); >>>> + >>>> audit_core_dumps(siginfo->si_signo); >>>> >>>> binfmt = mm->binfmt; >>>> diff --git a/kernel/task_work.c b/kernel/task_work.c >>>> index 1698fbe6f0e1..1ab28904adc4 100644 >>>> --- a/kernel/task_work.c >>>> +++ b/kernel/task_work.c >>>> @@ -41,6 +41,12 @@ int task_work_add(struct task_struct *task, struct callback_head *work, >>>> head = READ_ONCE(task->task_works); >>>> if (unlikely(head == &work_exited)) >>>> return -ESRCH; >>>> + /* >>>> + * TIF_NOTIFY_SIGNAL notifications will interfere with >>>> + * a core dump in progress, reject them. >>>> + */ >>>> + if ((task->flags & PF_SIGNALED) && notify == TWA_SIGNAL) >>>> + return -ESRCH; >>>> work->next = head; >>>> } while (cmpxchg(&task->task_works, head, work) != head); >>>> >>>> >>> Doesn't compile. 5.10 doesn't have TIF_NOTIFY_SIGNAL. >> Oh right... Here's one hacked up for the 5.10 TWA_SIGNAL setup. Totally >> untested... >> >> diff --git a/fs/coredump.c b/fs/coredump.c >> index c6acfc694f65..9e899ce67589 100644 >> --- a/fs/coredump.c >> +++ b/fs/coredump.c >> @@ -603,6 +603,19 @@ void do_coredump(const kernel_siginfo_t *siginfo) >> .mm_flags = mm->flags, >> }; >> >> + /* >> + * task_work_add() will refuse to add work after PF_SIGNALED has >> + * been set, ensure that we flush any pending TWA_SIGNAL work >> + * if any was queued before that. >> + */ >> + if (signal_pending(current) && (current->jobctl & JOBCTL_TASK_WORK)) { >> + task_work_run(); >> + spin_lock_irq(¤t->sighand->siglock); >> + current->jobctl &= ~JOBCTL_TASK_WORK; >> + recalc_sigpending(); >> + spin_unlock_irq(¤t->sighand->siglock); >> + } >> + >> audit_core_dumps(siginfo->si_signo); >> >> binfmt = mm->binfmt; >> diff --git a/kernel/task_work.c b/kernel/task_work.c >> index 8d6e1217c451..93b3f262eb4a 100644 >> --- a/kernel/task_work.c >> +++ b/kernel/task_work.c >> @@ -39,6 +39,12 @@ int task_work_add(struct task_struct *task, struct callback_head *work, >> head = READ_ONCE(task->task_works); >> if (unlikely(head == &work_exited)) >> return -ESRCH; >> + /* >> + * TWA_SIGNAL notifications will interfere with >> + * a core dump in progress, reject them. >> + */ >> + if ((task->flags & PF_SIGNALED) && notify == TWA_SIGNAL) >> + return -ESRCH; >> work->next = head; >> } while (cmpxchg(&task->task_works, head, work) != head); >> >> > Tested with 5.10.59 + backport 06af8679449d + the patch above. That > fixes it for me. I tested a couple of variations to make sure. > > Thanks! > > Tested-by: Tony Battersby Great, thanks for testing! The 5.10 version is a bit uglier due to how TWA_SIGNAL used to work, but it's the most straight forward backport of the other version I sent. -- Jens Axboe