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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no 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 1557FC2BA2B for ; Fri, 17 Apr 2020 02:17:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DCDF6221E9 for ; Fri, 17 Apr 2020 02:17:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729153AbgDQCR5 convert rfc822-to-8bit (ORCPT ); Thu, 16 Apr 2020 22:17:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:33900 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729095AbgDQCR4 (ORCPT ); Thu, 16 Apr 2020 22:17:56 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 53DAE206B9; Fri, 17 Apr 2020 02:17:55 +0000 (UTC) Date: Thu, 16 Apr 2020 22:17:53 -0400 From: Steven Rostedt To: Qian Cai Cc: Michael Ellerman , Russell Currey , Nicholas Piggin , linuxppc-dev , LKML Subject: Re: POWER9 crash due to STRICT_KERNEL_RWX (WAS: Re: Linux-next POWER9 NULL pointer NIP...) Message-ID: <20200416221753.4e47080a@oasis.local.home> In-Reply-To: <69F0448F-CA5B-497D-B8AF-2848175B9477@lca.pw> References: <15AC5B0E-A221-4B8C-9039-FA96B8EF7C88@lca.pw> <87eeszlb6u.fsf@mpe.ellerman.id.au> <0675B22E-8F32-432C-9378-FDE159DD1729@lca.pw> <20200407093054.3eb23e45@gandalf.local.home> <20200409101413.35d9c72d@gandalf.local.home> <06A2EA93-B730-4DB1-819F-D27E7032F0B3@lca.pw> <161662E3-5D9C-4C15-919C-CFEFE4CC35CB@lca.pw> <69F0448F-CA5B-497D-B8AF-2848175B9477@lca.pw> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 16 Apr 2020 21:19:10 -0400 Qian Cai wrote: > OK, reverted the commit, > > c55d7b5e6426 (“powerpc: Remove STRICT_KERNEL_RWX incompatibility with RELOCATABLE”) > > or set STRICT_KERNEL_RWX=n fixed the crash below and also mentioned in this thread, This may be a symptom and not a cure. > > https://lore.kernel.org/lkml/15AC5B0E-A221-4B8C-9039-FA96B8EF7C88@lca.pw/ > > [ 148.110969][T13115] LTP: starting chown04_16 > [ 148.255048][T13380] kernel tried to execute exec-protected page (c0000000016804ac) - exploit attempt? (uid: 0) > [ 148.255099][T13380] BUG: Unable to handle kernel instruction fetch > [ 148.255122][T13380] Faulting instruction address: 0xc0000000016804ac > [ 148.255136][T13380] Oops: Kernel access of bad area, sig: 11 [#1] > [ 148.255157][T13380] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA PowerNV > [ 148.255171][T13380] Modules linked in: loop kvm_hv kvm xfs sd_mod bnx2x mdio ahci tg3 libahci libphy libata firmware_class dm_mirror dm_region_hash dm_log dm_mod > [ 148.255213][T13380] CPU: 45 PID: 13380 Comm: chown04_16 Tainted: G W 5.6.0+ #7 > [ 148.255236][T13380] NIP: c0000000016804ac LR: c00800000fa60408 CTR: c0000000016804ac > [ 148.255250][T13380] REGS: c0000010a6fafa00 TRAP: 0400 Tainted: G W (5.6.0+) > [ 148.255281][T13380] MSR: 9000000010009033 CR: 84000248 XER: 20040000 > [ 148.255310][T13380] CFAR: c00800000fa66534 IRQMASK: 0 > [ 148.255310][T13380] GPR00: c000000000973268 c0000010a6fafc90 c000000001648200 0000000000000000 > [ 148.255310][T13380] GPR04: c000000d8a22dc00 c0000010a6fafd30 00000000b5e98331 ffffffff00012c9f > [ 148.255310][T13380] GPR08: c000000d8a22dc00 0000000000000000 0000000000000000 c00000000163c520 > [ 148.255310][T13380] GPR12: c0000000016804ac c000001ffffdad80 0000000000000000 0000000000000000 > [ 148.255310][T13380] GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 148.255310][T13380] GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 148.255310][T13380] GPR24: 00007fff8f5e2e48 0000000000000000 c00800000fa6a488 c0000010a6fafd30 > [ 148.255310][T13380] GPR28: 0000000000000000 000000007fffffff c00800000fa60400 c000000efd0c6780 > [ 148.255494][T13380] NIP [c0000000016804ac] sysctl_net_busy_read+0x0/0x4 The instruction pointer is on sysctl_net_busy_read? Isn't that data and not code? In net/socket.c: #ifdef CONFIG_NET_RX_BUSY_POLL unsigned int sysctl_net_busy_read __read_mostly; unsigned int sysctl_net_busy_poll __read_mostly; #endif -- Steve > [ 148.255516][T13380] LR [c00800000fa60408] find_free_cb+0x8/0x30 [loop] > [ 148.255528][T13380] Call Trace: > [ 148.255538][T13380] [c0000010a6fafc90] [c0000000009732c0] idr_for_each+0xf0/0x170 (unreliable) > [ 148.255572][T13380] [c0000010a6fafd10] [c00800000fa626c4] loop_lookup.part.1+0x4c/0xb0 [loop] > [ 148.255597][T13380] [c0000010a6fafd50] [c00800000fa634d8] loop_control_ioctl+0x120/0x1d0 [loop] > [ 148.255623][T13380] [c0000010a6fafdb0] [c0000000004ddc08] ksys_ioctl+0xd8/0x130 > [ 148.255636][T13380] [c0000010a6fafe00] [c0000000004ddc88] sys_ioctl+0x28/0x40 > [ 148.255669][T13380] [c0000010a6fafe20] [c00000000000b378] system_call+0x5c/0x68 > [ 148.255699][T13380] Instruction dump: > [ 148.255718][T13380] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX > [ 148.255744][T13380] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX > [ 148.255772][T13380] ---[ end trace a5894a74208c22ec ]--- > [ 148.576663][T13380] > [ 149.576765][T13380] Kernel panic - not syncing: Fatal exception >