From patchwork Thu Jan 10 21:09:34 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Khalid Aziz X-Patchwork-Id: 10756901 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2D2E113B5 for ; Thu, 10 Jan 2019 21:11:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1D61E29BD7 for ; Thu, 10 Jan 2019 21:11:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0F80A29BE7; Thu, 10 Jan 2019 21:11:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 2833629BD2 for ; Thu, 10 Jan 2019 21:10:58 +0000 (UTC) Received: (qmail 9288 invoked by uid 550); 10 Jan 2019 21:10:50 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 9223 invoked from network); 10 Jan 2019 21:10:49 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : in-reply-to : references; s=corp-2018-07-02; bh=rxloVUR5hTpog4EkfpKEBfCxP1GI1EsadkVaOQCjD2o=; b=1CYkyUJc4Qs2o0butOq1ThTUw0aGOHhtGvgscR/9iH/yWacmRM01oZvKfD4Gt31YBLEM ce9ixyvlKWNm/xwoNnMIWXjHRhkJlHhKG7fBtz1G2ss13MtAzB1P+0ZMGeWdtgi4T0dq dIcMgf+jX0Jelv8dbvcLwmQz2WNq6a2d+1eNlp91l4a45r45cp5GH4GY4pnQpLkQv2wb VcVhVfb4sHJ3GpJ9krKLY7oSD+xhZEwYCYbOWVMEhq0EL+RRT4bkWE+i9wcDPueGbJ7B P7HJ8t2860x1dpq4pYilUvGWzzNx1DUnQxLD7dk3BC/9AkpMY9iRoAeGOYUL8Cme3mQO kA== From: Khalid Aziz To: juergh@gmail.com, tycho@tycho.ws, jsteckli@amazon.de, ak@linux.intel.com, torvalds@linux-foundation.org, liran.alon@oracle.com, keescook@google.com, konrad.wilk@oracle.com Cc: Tycho Andersen , deepa.srinivasan@oracle.com, chris.hyser@oracle.com, tyhicks@canonical.com, dwmw@amazon.co.uk, andrew.cooper3@citrix.com, jcm@redhat.com, boris.ostrovsky@oracle.com, kanth.ghatraju@oracle.com, joao.m.martins@oracle.com, jmattson@google.com, pradeep.vincent@oracle.com, john.haxby@oracle.com, tglx@linutronix.de, kirill.shutemov@linux.intel.com, hch@lst.de, steven.sistare@oracle.com, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, Khalid Aziz Subject: [RFC PATCH v7 02/16] x86: always set IF before oopsing from page fault Date: Thu, 10 Jan 2019 14:09:34 -0700 Message-Id: <46b0f1a61dabf6440d461c063a32573b96f3a5ce.1547153058.git.khalid.aziz@oracle.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: References: In-Reply-To: References: X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9132 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=953 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1901100164 X-Virus-Scanned: ClamAV using ClamSMTP From: Tycho Andersen Oopsing might kill the task, via rewind_stack_do_exit() at the bottom, and that might sleep: Aug 23 19:30:27 xpfo kernel: [ 38.302714] BUG: sleeping function called from invalid context at ./include/linux/percpu-rwsem.h:33 Aug 23 19:30:27 xpfo kernel: [ 38.303837] in_atomic(): 0, irqs_disabled(): 1, pid: 1970, name: lkdtm_xpfo_test Aug 23 19:30:27 xpfo kernel: [ 38.304758] CPU: 3 PID: 1970 Comm: lkdtm_xpfo_test Tainted: G D 4.13.0-rc5+ #228 Aug 23 19:30:27 xpfo kernel: [ 38.305813] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1ubuntu1 04/01/2014 Aug 23 19:30:27 xpfo kernel: [ 38.306926] Call Trace: Aug 23 19:30:27 xpfo kernel: [ 38.307243] dump_stack+0x63/0x8b Aug 23 19:30:27 xpfo kernel: [ 38.307665] ___might_sleep+0xec/0x110 Aug 23 19:30:27 xpfo kernel: [ 38.308139] __might_sleep+0x45/0x80 Aug 23 19:30:27 xpfo kernel: [ 38.308593] exit_signals+0x21/0x1c0 Aug 23 19:30:27 xpfo kernel: [ 38.309046] ? blocking_notifier_call_chain+0x11/0x20 Aug 23 19:30:27 xpfo kernel: [ 38.309677] do_exit+0x98/0xbf0 Aug 23 19:30:27 xpfo kernel: [ 38.310078] ? smp_reader+0x27/0x40 [lkdtm] Aug 23 19:30:27 xpfo kernel: [ 38.310604] ? kthread+0x10f/0x150 Aug 23 19:30:27 xpfo kernel: [ 38.311045] ? read_user_with_flags+0x60/0x60 [lkdtm] Aug 23 19:30:27 xpfo kernel: [ 38.311680] rewind_stack_do_exit+0x17/0x20 To be safe, let's just always enable irqs. The particular case I'm hitting is: Aug 23 19:30:27 xpfo kernel: [ 38.278615] __bad_area_nosemaphore+0x1a9/0x1d0 Aug 23 19:30:27 xpfo kernel: [ 38.278617] bad_area_nosemaphore+0xf/0x20 Aug 23 19:30:27 xpfo kernel: [ 38.278618] __do_page_fault+0xd1/0x540 Aug 23 19:30:27 xpfo kernel: [ 38.278620] ? irq_work_queue+0x9b/0xb0 Aug 23 19:30:27 xpfo kernel: [ 38.278623] ? wake_up_klogd+0x36/0x40 Aug 23 19:30:27 xpfo kernel: [ 38.278624] trace_do_page_fault+0x3c/0xf0 Aug 23 19:30:27 xpfo kernel: [ 38.278625] do_async_page_fault+0x14/0x60 Aug 23 19:30:27 xpfo kernel: [ 38.278627] async_page_fault+0x28/0x30 When a fault is in kernel space which has been triggered by XPFO. Signed-off-by: Tycho Andersen CC: x86@kernel.org Signed-off-by: Khalid Aziz --- arch/x86/mm/fault.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 71d4b9d4d43f..ba51652fbd33 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -748,6 +748,12 @@ no_context(struct pt_regs *regs, unsigned long error_code, /* Executive summary in case the body of the oops scrolled away */ printk(KERN_DEFAULT "CR2: %016lx\n", address); + /* + * We're about to oops, which might kill the task. Make sure we're + * allowed to sleep. + */ + flags |= X86_EFLAGS_IF; + oops_end(flags, regs, sig); }