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=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,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 50C0CC3F2D1 for ; Fri, 6 Mar 2020 00:27:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 339F420705 for ; Fri, 6 Mar 2020 00:27:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727066AbgCFA1q (ORCPT ); Thu, 5 Mar 2020 19:27:46 -0500 Received: from ozlabs.org ([203.11.71.1]:52437 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726184AbgCFA1o (ORCPT ); Thu, 5 Mar 2020 19:27:44 -0500 Received: by ozlabs.org (Postfix, from userid 1034) id 48YT3L2PZzz9sSV; Fri, 6 Mar 2020 11:27:42 +1100 (AEDT) X-powerpc-patch-notification: thanks X-powerpc-patch-commit: a83836dbc53e96f13fec248ecc201d18e1e3111d In-Reply-To: <20200131132829.10281-1-msuchanek@suse.de> To: Michal Suchanek , linuxppc-dev@lists.ozlabs.org, Nathan Lynch , Libor Pechacek From: Michael Ellerman Cc: David Hildenbrand , Michal Suchanek , stable@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Mackerras , Leonardo Bras , Thomas Gleixner , Michal Suchanek , Allison Randal Subject: Re: [PATCH v2] powerpc: drmem: avoid NULL pointer dereference when drmem is unavailable Message-Id: <48YT3L2PZzz9sSV@ozlabs.org> Date: Fri, 6 Mar 2020 11:27:42 +1100 (AEDT) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, 2020-01-31 at 13:28:29 UTC, Michal Suchanek wrote: > > From: Libor Pechacek > > In guests without hotplugagble memory drmem structure is only zero > initialized. Trying to manipulate DLPAR parameters results in a crash. > > $ echo "memory add count 1" > /sys/kernel/dlpar > Oops: Kernel access of bad area, sig: 11 [#1] > LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries > Modules linked in: af_packet(E) rfkill(E) nvram(E) vmx_crypto(E) > gf128mul(E) e1000(E) virtio_balloon(E) rtc_generic(E) crct10dif_vpmsum(E) > btrfs(E) blake2b_generic(E) libcrc32c(E) xor(E) raid6_pq(E) virtio_rng(E) > virtio_blk(E) ohci_pci(E) ehci_pci(E) ohci_hcd(E) ehci_hcd(E) > crc32c_vpmsum(E) usbcore(E) virtio_pci(E) virtio_ring(E) virtio(E) sg(E) > dm_multipath(E) dm_mod(E) scsi_dh_rdac(E) scsi_dh_emc(E) scsi_dh_alua(E) > scsi_mod(E) > CPU: 1 PID: 4114 Comm: bash Kdump: loaded Tainted: G E 5.5.0-rc6-2-default #1 > NIP: c0000000000ff294 LR: c0000000000ff248 CTR: 0000000000000000 > REGS: c0000000fb9d3880 TRAP: 0300 Tainted: G E (5.5.0-rc6-2-default) > MSR: 8000000000009033 CR: 28242428 XER: 20000000 > CFAR: c0000000009a6c10 DAR: 0000000000000010 DSISR: 40000000 IRQMASK: 0 > GPR00: c0000000000ff248 c0000000fb9d3b10 c000000001682e00 0000000000000033 > GPR04: c0000000ff30bf90 c0000000ff394800 0000000000005110 ffffffffffffffe8 > GPR08: 0000000000000000 0000000000000000 00000000fe1c0000 0000000000000000 > GPR12: 0000000000002200 c00000003fffee00 0000000000000000 000000011cbc37c0 > GPR16: 000000011cb27ed0 0000000000000000 000000011cb6dd10 0000000000000000 > GPR20: 000000011cb7db28 000001003ce035f0 000000011cbc7828 000000011cbc6c70 > GPR24: 000001003cf01210 0000000000000000 c0000000ffade4e0 c000000002d7216b > GPR28: 0000000000000001 c000000002d78560 0000000000000000 c0000000015458d0 > NIP [c0000000000ff294] dlpar_memory+0x6e4/0xd00 > LR [c0000000000ff248] dlpar_memory+0x698/0xd00 > Call Trace: > [c0000000fb9d3b10] [c0000000000ff248] dlpar_memory+0x698/0xd00 (unreliable) > [c0000000fb9d3ba0] [c0000000000f5990] handle_dlpar_errorlog+0xc0/0x190 > [c0000000fb9d3c10] [c0000000000f5c58] dlpar_store+0x198/0x4a0 > [c0000000fb9d3cd0] [c000000000c4cb00] kobj_attr_store+0x30/0x50 > [c0000000fb9d3cf0] [c0000000005a37b4] sysfs_kf_write+0x64/0x90 > [c0000000fb9d3d10] [c0000000005a2c90] kernfs_fop_write+0x1b0/0x290 > [c0000000fb9d3d60] [c0000000004a2bec] __vfs_write+0x3c/0x70 > [c0000000fb9d3d80] [c0000000004a6560] vfs_write+0xd0/0x260 > [c0000000fb9d3dd0] [c0000000004a69ac] ksys_write+0xdc/0x130 > [c0000000fb9d3e20] [c00000000000b478] system_call+0x5c/0x68 > Instruction dump: > ebc90000 1ce70018 38e7ffe8 7cfe3a14 7fbe3840 419dff14 fb610068 7fc9f378 > 39000000 4800000c 60000000 4195fef4 <81490010> 39290018 38c80001 7ea93840 > ---[ end trace cc2dd8152608c295 ]--- > > Taking closer look at the code, I can see that for_each_drmem_lmb is a > macro expanding into `for (lmb = &drmem_info->lmbs[0]; lmb <= > &drmem_info->lmbs[drmem_info->n_lmbs - 1]; lmb++)`. When drmem_info->lmbs > is NULL, the loop would iterate through the whole address range if it > weren't stopped by the NULL pointer dereference on the next line. > > This patch aligns for_each_drmem_lmb and for_each_drmem_lmb_in_range macro > behavior with the common C semantics, where the end marker does not belong > to the scanned range, and alters get_lmb_range() semantics. As a side > effect, the wraparound observed in the crash is prevented. > > Fixes: 6c6ea53725b3 ("powerpc/mm: Separate ibm, dynamic-memory data from DT format") > Cc: Michal Suchanek > Cc: stable@vger.kernel.org > Signed-off-by: Libor Pechacek > Signed-off-by: Michal Suchanek Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/a83836dbc53e96f13fec248ecc201d18e1e3111d cheers