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X-CSE-ConnectionGUID: yIRJJuncSbiX/SvYgi7Zrg== X-CSE-MsgGUID: mZRZuqV/Rg+lnXsLm7CY4Q== X-IronPort-AV: E=McAfee;i="6700,10204,11254"; a="42670017" X-IronPort-AV: E=Sophos;i="6.12,148,1728975600"; d="scan'208";a="42670017" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Nov 2024 09:15:06 -0800 X-CSE-ConnectionGUID: IdqbexO0TrKoY2Nu4Mzapw== X-CSE-MsgGUID: h/nSa3DBTIie7Dy2ZZRWwg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,148,1728975600"; d="scan'208";a="88005627" Received: from jairdeje-mobl1.amr.corp.intel.com (HELO [10.124.220.61]) ([10.124.220.61]) by fmviesa009-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Nov 2024 09:15:05 -0800 Message-ID: <001092d4-8431-488b-a98d-3aa5d4ecb692@intel.com> Date: Tue, 12 Nov 2024 09:15:05 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC][PATCH] x86/cpu/bugs: Consider having old Intel microcode to be a vulnerability To: Andrew Cooper , dave.hansen@linux.intel.com Cc: bp@alien8.de, linux-kernel@vger.kernel.org, tglx@linutronix.de, x86@kernel.org References: <20241107170630.2A92B8D3@davehans-spike.ostc.intel.com> <59718ea7-efab-4975-a4e8-89c1d114a2e5@citrix.com> Content-Language: en-US From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 11/8/24 15:36, Andrew Cooper wrote: >> You can't practically run old microcode and consider a system secure >> these days. So, let's call old microcode what it is: a vulnerability. > > The list becomes stale 4 times a year, so you need to identify when it's > out of date, and whatever that something is has to be strong enough to > cause distros to backport too.  Perhaps a date in the header, so you can > at least report "status vulnerable, metadata out of date". I don't want to get too fancy about this. I'm assuming that mainline and the stable kernels will be regularly fed new metadata. The only way to have out-of-date metadata should be by running an out-of-date kernel in which case you have bigger problems on your hands. > Also, you want to identify EOL CPUs.  Just because they're on the most > recent published ucode doesn't mean they're not vulnerable. That's a good idea too. But I think it deserves a separate discussion and separate patch. > Under some hypervisors, you get fed the revision 0x7fffffff.  Others > might tell you the truth, or it may be the truth from when you booted.  > For this, probably best to say "consult your hypervisor". Good point. We should probably just say "unknown" when running as a guest, or just not have the sysfs file at all. > Failure to publish information, or not publishing fixes for in-support > parts should be considered a vulnerability.  (*ahem*, AMD) > > Or you could just simplify the whole path to "yes".  It's true, even if > people don't know. This series answers the question: Has the vendor published a newer OS-loadable microcode than you are running right now? It doesn't seek to answer the question: Is the microcode that you are running right now vulnerable to anything (that the kernel knows about)? I think the first question is quite answerable in a pretty factual way. The second question is much hardware. It's worth answering for sure ... with another patch. :)