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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 28699C433EF for ; Wed, 8 Sep 2021 11:34:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 03ADF61158 for ; Wed, 8 Sep 2021 11:34:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348769AbhIHLfe (ORCPT ); Wed, 8 Sep 2021 07:35:34 -0400 Received: from mail.skyhub.de ([5.9.137.197]:39450 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348557AbhIHLfe (ORCPT ); Wed, 8 Sep 2021 07:35:34 -0400 Received: from zn.tnic (p200300ec2f0efc002d1ac0b1b41b9169.dip0.t-ipconnect.de [IPv6:2003:ec:2f0e:fc00:2d1a:c0b1:b41b:9169]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 69E191EC036B; Wed, 8 Sep 2021 13:34:25 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1631100865; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=m/Frv4i98ljsymrvV0/yhoTmQ0S/VberekuyvlZ3qEw=; b=NfKUxhqk7CQNY9baqIi2HJw9km0ov3Vhu96MRbZd7TFmRoLJn/9d8b11Xk17XDIwl6B1Wg ubT9iwlULRlwmbhdS1woU5AIwJtXvDZL2VpfRLDE9rroVJfb1kI8NRVVH/gFIGNGu7QkLI 7I/ZsdGgnHAzL2v1JqKR3QArzp0xr0w= Date: Wed, 8 Sep 2021 13:34:18 +0200 From: Borislav Petkov To: Mike Rapoport Cc: Dave Hansen , x86@kernel.org, Andrew Morton , Andy Lutomirski , Dave Hansen , David Hildenbrand , Ingo Molnar , Jiri Olsa , Mike Rapoport , Oscar Salvador , Peter Zijlstra , Thomas Gleixner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] x86/mm: fix kern_addr_valid to cope with existing but not present entries Message-ID: References: <20210819132717.19358-1-rppt@kernel.org> <35f4a263-1001-5ba5-7b6c-3fcc5f93cc30@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Wed, Sep 08, 2021 at 02:22:31PM +0300, Mike Rapoport wrote: > kern_addr_valid() wrongly uses pxy_none() rather than pxy_present() because > according to 9a14aefc1d28 ("x86: cpa, fix lookup_address") there could be > cases when page table entries exist but they are not valid. > So a call to kern_addr_valid() for an address in the direct map would oops. > > I've stopped digging at 9a14aefc1d28 (which is in v2.6.26) and added the > oldest stable we still support (4.4). > > I agree that before 4.19 it's more of a theoretical bug, but you know, > things happen... Hmmkay, I guess I should add the gist of that to the commit message so that it is explained why 4.4. I'm assuming the pxy_present() check is more strict than pxy_none() so that backporting to all stable kernels should not introduce any risks... -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette