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Wed, 25 Mar 2020 12:15:13 +0000 Received: from BL0PR11MB3281.namprd11.prod.outlook.com ([fe80::e0a0:7b4b:3824:17e6]) by BL0PR11MB3281.namprd11.prod.outlook.com ([fe80::e0a0:7b4b:3824:17e6%7]) with mapi id 15.20.2835.023; Wed, 25 Mar 2020 12:15:13 +0000 From: "Reshetova, Elena" To: Kees Cook , Jann Horn CC: Thomas Gleixner , the arch/x86 maintainers , Andy Lutomirski , Peter Zijlstra , Catalin Marinas , "Will Deacon" , Mark Rutland , "Alexander Potapenko" , Ard Biesheuvel , Kernel Hardening , "linux-arm-kernel@lists.infradead.org" , Linux-MM , kernel list Subject: RE: [PATCH v2 0/5] Optionally randomize kernel stack offset each syscall Thread-Topic: [PATCH v2 0/5] Optionally randomize kernel stack offset each syscall Thread-Index: AQHWAhtwq3buLIhNY0uHCAE/uJPRC6hYQiKAgAAbvoCAANt94A== Date: Wed, 25 Mar 2020 12:15:12 +0000 Message-ID: References: <20200324203231.64324-1-keescook@chromium.org> <202003241604.7269C810B@keescook> In-Reply-To: <202003241604.7269C810B@keescook> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-version: 11.2.0.6 dlp-product: dlpe-windows dlp-reaction: no-action authentication-results: spf=none (sender IP is ) smtp.mailfrom=elena.reshetova@intel.com; x-originating-ip: [193.210.230.89] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 9b4fbd89-f70c-4462-79a3-08d7d0b62bb6 x-ms-traffictypediagnostic: BL0PR11MB3220: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:7219; x-forefront-prvs: 0353563E2B x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(366004)(376002)(136003)(396003)(39860400002)(346002)(5660300002)(66946007)(6506007)(66476007)(7416002)(2906002)(26005)(52536014)(66556008)(64756008)(66446008)(33656002)(76116006)(55016002)(86362001)(81156014)(81166006)(8936002)(8676002)(9686003)(71200400001)(4326008)(478600001)(186003)(7696005)(54906003)(110136005)(316002)(4744005);DIR:OUT;SFP:1102;SCL:1;SRVR:BL0PR11MB3220;H:BL0PR11MB3281.namprd11.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: R0fHfiHe8IwDhu/PudqxvcDZ+HOwdID1+Ng9PLiwh0AO1XId7kD5n6/N6KkV53W4qA5fCWm1kMve7REZUR8b7tfsZ0qwzO1SbmzfzUQuTef3Q+RWQizkUkYOeFdNG9QLqnsGNyhhKpTeHHKHAoC4GFvWo4/fjB1EaC3+6oQRGRJcBSyXd9ZvKE2SnVVzKJZ7Zrd1BNOW8gk+0CDvQ1pE6PEAionQk/bCbpGWMP+cjfucQM5Iz8gOvPfOvt2jSzXH/ZVO2yeoHuhQzV8ijn20hPRMlKrV9A697E5gJICuCt6rqGUznVewzCHr1aUmYKoLmo3n21Xj6AA7+LQwriDcfqXX9+3uFAoupeeHwP8GgrAiYmz9N3XQHDgLpgpEqXlL2z+735Dt1q/0R88sYS8pxh9HILua5BGYthTXDBiP8bmt1Bi2Plg/wkUSdnnJenMP x-ms-exchange-antispam-messagedata: /CNCpOp659D172WBicTizC4uCv6sPoROncMCkc7ljYWplLv4kJ8C/Ss7dwBTKoPT+B9cN+1DoEN/AQPs7mMyIYvDkPMoQMYW4Gi/KGoDUcdz3XyyuTKwfhNpVkmCtSxcrVO1oEa6sESZV3nQbrXr5A== x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 9b4fbd89-f70c-4462-79a3-08d7d0b62bb6 X-MS-Exchange-CrossTenant-originalarrivaltime: 25 Mar 2020 12:15:12.9820 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: 9BUpkDalH6Xfnn9q/Z4fatBvI6iYdf5wUeTPr7aT+6vnesukWh+gAF4FEkKMS4KS4GMmteUqxdITni7Y6iZK8dHgLLKOWqP5PLikRjEu6Ew= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR11MB3220 X-OriginatorOrg: intel.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > Also, are you sure that it isn't possible to make the syscall that > > leaked its stack pointer never return to userspace (via ptrace or > > SIGSTOP or something like that), and therefore never realign its > > stack, while keeping some controlled data present on the syscall's > > stack? How would you reliably detect that a stack pointer has been leaked to userspace while it has been in a syscall? Does not seem to be a trivial task to me.=20 Best Regards, Elena.=20