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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 3AD0AC2BB55 for ; Thu, 16 Apr 2020 14:19:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F7DA2063A for ; Thu, 16 Apr 2020 14:19:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587046768; bh=GsCdRkH6Shz5a43jOx+xZYYuDbINTK0YiB1BnatUcgQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NsK7Jr4E8sjCc5A/JNc5Xo+aWcXfpq4AkYdZUyHnUw3UILnm3nBBSu+Z+ebEmtavT gotZ7pblbhVE4ZARwxLGhawtg6aQALZ4fq3N8IJ0fMMpLaxI8S9xdftL5Q6pBFPd7e u7hdNTd/6txxfylZ24xfbfqGnlFBlnn4x8UufyZw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2442455AbgDPOTY (ORCPT ); Thu, 16 Apr 2020 10:19:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:40608 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2898638AbgDPNyE (ORCPT ); Thu, 16 Apr 2020 09:54:04 -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 CA3AA20732; Thu, 16 Apr 2020 13:54:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587045244; bh=GsCdRkH6Shz5a43jOx+xZYYuDbINTK0YiB1BnatUcgQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=f6VT7a4a36hodGbsP87ZRBAIozVBTPLw4GfDnfGXD/mdCECE7QOjBV+rx9sflJrpR 8QDjxC0P6VCPt2DNtLfpyAoDJD2CzaUI8W/za+iNJEq7Yt/KG5Atyhl/8f+B5rELvW /gEU0aNqGgdpDck1Qu//S6HI6wtQ4IZhWq1HEOC4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Hildenbrand , Mark Rutland , Catalin Marinas , Steven Price , Anshuman Khandual , Sasha Levin Subject: [PATCH 5.6 014/254] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump Date: Thu, 16 Apr 2020 15:21:43 +0200 Message-Id: <20200416131327.591440866@linuxfoundation.org> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200416131325.804095985@linuxfoundation.org> References: <20200416131325.804095985@linuxfoundation.org> User-Agent: quilt/0.66 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 From: Anshuman Khandual [ Upstream commit bf2b59f60ee1fefa768d62ec6e8f4b4d9e04c691 ] The arm64 page table dump code can race with concurrent modification of the kernel page tables. When a leaf entries are modified concurrently, the dump code may log stale or inconsistent information for a VA range, but this is otherwise not harmful. When intermediate levels of table are freed, the dump code will continue to use memory which has been freed and potentially reallocated for another purpose. In such cases, the dump code may dereference bogus addresses, leading to a number of potential problems. Intermediate levels of table may by freed during memory hot-remove, which will be enabled by a subsequent patch. To avoid racing with this, take the memory hotplug lock when walking the kernel page table. Acked-by: David Hildenbrand Acked-by: Mark Rutland Acked-by: Catalin Marinas Reviewed-by: Steven Price Signed-off-by: Anshuman Khandual Signed-off-by: Catalin Marinas Signed-off-by: Sasha Levin --- arch/arm64/mm/ptdump_debugfs.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm64/mm/ptdump_debugfs.c b/arch/arm64/mm/ptdump_debugfs.c index 1f2eae3e988b6..d29d722ec3ec6 100644 --- a/arch/arm64/mm/ptdump_debugfs.c +++ b/arch/arm64/mm/ptdump_debugfs.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include #include #include @@ -7,7 +8,10 @@ static int ptdump_show(struct seq_file *m, void *v) { struct ptdump_info *info = m->private; + + get_online_mems(); ptdump_walk(m, info); + put_online_mems(); return 0; } DEFINE_SHOW_ATTRIBUTE(ptdump); -- 2.20.1