From patchwork Thu Apr 16 13:24:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 227532 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 B7200C2BB55 for ; Thu, 16 Apr 2020 15:54:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F8BA214AF for ; Thu, 16 Apr 2020 15:54:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587052483; bh=xqhYctsbPYWAQFJ5JpgiISPALWCmUCtnpQ4HqLrMCZw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=izWohIFXzc+gVMaSFB898kVk5VoZR98ufNLl7W+vwUPiKQxY0Qau/buFQGcJlR9wn meqwxoauFNjjF4wLwQ01qV/fyaZvtae+HiUsyzr2PsBr7EZf37gYE5nrvaq2hzVkeX LunhKOkx4L0yvj9pd3o2+giJFcBxqLhhqQjGwnbo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2441905AbgDPPyl (ORCPT ); Thu, 16 Apr 2020 11:54:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:40394 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2895908AbgDPNaN (ORCPT ); Thu, 16 Apr 2020 09:30:13 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 3D4F0208E4; Thu, 16 Apr 2020 13:30:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587043812; bh=xqhYctsbPYWAQFJ5JpgiISPALWCmUCtnpQ4HqLrMCZw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PRoWCA0ut7TR7FzwC5rEpc2KzVY3ul1MPSO9KAqDwKl1/kx/vgz5FGsoTnanpKhld lglkjbYj3obvrn7c8iWI385UW4bwKaZ4JLiTLDYFd9Gak/xBgOTXRd26MIkXLdoJhd g1kpkYZucRkcW7BNsxZ+NZMHKO9E0BVauPby2EG0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Libor Pechacek , Michal Suchanek , Michael Ellerman Subject: [PATCH 4.19 109/146] powerpc/pseries: Avoid NULL pointer dereference when drmem is unavailable Date: Thu, 16 Apr 2020 15:24:10 +0200 Message-Id: <20200416131257.595487715@linuxfoundation.org> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200416131242.353444678@linuxfoundation.org> References: <20200416131242.353444678@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Libor Pechacek commit a83836dbc53e96f13fec248ecc201d18e1e3111d upstream. 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 ... 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 ... NIP dlpar_memory+0x6e4/0xd00 LR dlpar_memory+0x698/0xd00 Call Trace: dlpar_memory+0x698/0xd00 (unreliable) handle_dlpar_errorlog+0xc0/0x190 dlpar_store+0x198/0x4a0 kobj_attr_store+0x30/0x50 sysfs_kf_write+0x64/0x90 kernfs_fop_write+0x1b0/0x290 __vfs_write+0x3c/0x70 vfs_write+0xd0/0x260 ksys_write+0xdc/0x130 system_call+0x5c/0x68 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: stable@vger.kernel.org # v4.16+ Signed-off-by: Libor Pechacek Signed-off-by: Michal Suchanek Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200131132829.10281-1-msuchanek@suse.de Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/include/asm/drmem.h | 4 ++-- arch/powerpc/platforms/pseries/hotplug-memory.c | 8 ++++---- 2 files changed, 6 insertions(+), 6 deletions(-) --- a/arch/powerpc/include/asm/drmem.h +++ b/arch/powerpc/include/asm/drmem.h @@ -28,12 +28,12 @@ struct drmem_lmb_info { extern struct drmem_lmb_info *drmem_info; #define for_each_drmem_lmb_in_range(lmb, start, end) \ - for ((lmb) = (start); (lmb) <= (end); (lmb)++) + for ((lmb) = (start); (lmb) < (end); (lmb)++) #define for_each_drmem_lmb(lmb) \ for_each_drmem_lmb_in_range((lmb), \ &drmem_info->lmbs[0], \ - &drmem_info->lmbs[drmem_info->n_lmbs - 1]) + &drmem_info->lmbs[drmem_info->n_lmbs]) /* * The of_drconf_cell_v1 struct defines the layout of the LMB data --- a/arch/powerpc/platforms/pseries/hotplug-memory.c +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c @@ -227,7 +227,7 @@ static int get_lmb_range(u32 drc_index, struct drmem_lmb **end_lmb) { struct drmem_lmb *lmb, *start, *end; - struct drmem_lmb *last_lmb; + struct drmem_lmb *limit; start = NULL; for_each_drmem_lmb(lmb) { @@ -240,10 +240,10 @@ static int get_lmb_range(u32 drc_index, if (!start) return -EINVAL; - end = &start[n_lmbs - 1]; + end = &start[n_lmbs]; - last_lmb = &drmem_info->lmbs[drmem_info->n_lmbs - 1]; - if (end > last_lmb) + limit = &drmem_info->lmbs[drmem_info->n_lmbs]; + if (end > limit) return -EINVAL; *start_lmb = start;