From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linutronix.de (146.0.238.70:993) by crypto-ml.lab.linutronix.de with IMAP4-SSL for ; 21 Feb 2019 19:26:09 -0000 Received: from mga01.intel.com ([192.55.52.88]) by Galois.linutronix.de with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1gwtyy-0001qk-DG for speck@linutronix.de; Thu, 21 Feb 2019 20:26:08 +0100 References: <20190220150753.665964899@linutronix.de> <20190220151400.306266355@linutronix.de> <20190220171009.GB127@mgross-MOBL.amr.corp.intel.com> From: Tim Chen Message-ID: Date: Thu, 21 Feb 2019 11:26:05 -0800 MIME-Version: 1.0 In-Reply-To: <20190220171009.GB127@mgross-MOBL.amr.corp.intel.com> Subject: [MODERATED] Encrypted Message Content-Type: multipart/mixed; boundary="390syE1AevCDZ4SxLSmsglWfdOiMtWSUv"; protected-headers="v1" To: speck@linutronix.de List-ID: This is an OpenPGP/MIME encrypted message (RFC 4880 and 3156) --390syE1AevCDZ4SxLSmsglWfdOiMtWSUv Content-Type: text/rfc822-headers; protected-headers="v1" Content-Disposition: inline From: Tim Chen To: speck for mark gross Subject: Re: [patch V2 04/10] MDS basics+ 4 --390syE1AevCDZ4SxLSmsglWfdOiMtWSUv Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2/20/19 9:10 AM, speck for mark gross wrote: >> + >> + - KGBD s/KGBD/KGDB >> + >> + If the kernel debugger is accessible by an unpriviledged atta= cker, >> + then the NMI handler is the least of the problems. >> + =2E.. >=20 > However; if I'm being pedantic, the attacker not having controlability = aspect > of your argument can apply to most aspects of the MDS vulnerability. I= think > that's why its name uses "data sampling". Also, I need to ask the chip= heads > about if this list of NMI's is complete and can be expected to stay tha= t way > across processor and platfrom generations. >=20 > --mark >=20 I don't think any of the code paths listed touches any user data. So eve= n if an attacker have some means to control NMI, he won't get any useful da= ta. Thanks. Tim=20 --390syE1AevCDZ4SxLSmsglWfdOiMtWSUv--