From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F089E2E641 for ; Wed, 6 Mar 2024 08:40:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709714414; cv=none; b=ubJNF2vyuMImCa87n4PyQn3iu1ygoY7JjnmofGHs9dFNaOqeu/4btQZ1FDWg281jBfSXh+5ouGpXd7IgtJ18uuxUto7EfyRg9C4qYBRy7Y2Ya10bZ512Z6Zh4OcReNepiFvEY/ofn4SyuLVfGQPnks4dIwI3cW0f6RdD8Gvpi5w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709714414; c=relaxed/simple; bh=ZuU3Syw6vHSb9m0W3SEXJ7dIREkCqdvYhwu5F4k7yyc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FQ8qAqUg0Wc/uUhl7Co17pnGhpzD0h2efG8M2JIOGE0FoN+plr4PqV5y/4S7kkM45osWM+bjEez1KRYPfmvgqqZQhdLjuQ8aYnVFFACSEh/7kvihO1XGIAZOA5H0R+G2GCKyYAcJGXOg2eXAr/ddwcccV0dvKb7lv8+lbKGKLMY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=T9M7Wjdr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="T9M7Wjdr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 514BFC433F1; Wed, 6 Mar 2024 08:40:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1709714413; bh=ZuU3Syw6vHSb9m0W3SEXJ7dIREkCqdvYhwu5F4k7yyc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=T9M7WjdrpeAhlVznzweK/LWO4Wx+OLPJ/MECehdCTU4ugWUYhj1gC62s+AM5leC/Z 81B6XJrnkpJLEwR6AY71tc5IfPLW3CZljpV4jzzSQLgYc1jMRvjHmwPUTpcdb4voe3 b/4jeyyTJSFmx6lamyM3NJGfW0nNR+SeV/lPEMhM= Date: Wed, 6 Mar 2024 08:40:10 +0000 From: Greg Kroah-Hartman To: Michal Hocko Cc: cve@kernel.org, linux-kernel@vger.kernel.org Subject: Re: CVE-2021-47090: mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page() Message-ID: <2024030651-drizzly-sanitizer-cba4@gregkh> References: <2024030413-CVE-2021-47090-a429@gregkh> <2024030541-unhappily-staff-8662@gregkh> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Mar 06, 2024 at 09:06:42AM +0100, Michal Hocko wrote: > On Tue 05-03-24 22:20:17, Greg KH wrote: > > On Tue, Mar 05, 2024 at 07:45:04PM +0100, Michal Hocko wrote: > > > On Mon 04-03-24 19:11:17, Greg KH wrote: > > > > Description > > > > =========== > > > > > > > > In the Linux kernel, the following vulnerability has been resolved: > > > > > > > > mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page() > > > > > > I would like to dispute this CVE. The interface is behind CAP_SYSADMIN > > > and allowing access to this to any untrusted party is risking serious > > > troubles. This is a testing only feature. > > > > This fixes a weakness in the kernel, one that is allowed to crash it, > > why isn't that a good thing to have a CVE entry for? Are we saying that > > all VM_BUG_ON_PAGE() instances should not be accounted for? That's not > > what the config option for CONFIG_DEBUG_VM says, it just says it will > > affect performance. > > I wouldn't personaly recommend anybody using CONFIG_DEBUG_VM=y in > production. But I am not questioning if somebody does that. This is > not really what I am objecting to. Hwpoisoning or soft offlining is not > aimed for other than testing purposes. Things can go wrong during > these oprations. Agreed, things can go wrong, but people use them for "reasons" otherwise we wouldn't have those options in the kernel at all. Because of that, this "fix for a weakness" was given a CVE, that's all. Again, we do not dictate use case, or severity at all, that's not our role. > If you insist this still qualifies as a vulnaribility/weakness fix then > I would propose a new category pig-with-a-lipstick-CVE. > > > Also /sys/devices/system/memory/soft_offline_page doesn't say "can crash > > the system", so it should work properly, even if an admin uses it, it > > shouldn't shut the box down. > > I agree that Documentation/ABI/testing/sysfs-memory-page-offline would > benefit from an update. Documentation/admin-guide/mm/memory-hotplug.rst > is explicit about this being a testing feature. The fact that I didn't even notice that is kind of proof that maybe others might also miss it :) thanks, greg k-h