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Lu" , Dave Martin , Jann Horn , Michael Ellerman , Carlos O'Donell , "Luck, Tony" , "Shankar, Ravi V" , libc-alpha , linux-arch , Linux API , LKML Subject: Re: [PATCH v7 5/6] x86/signal: Detect and prevent an alternate signal stack overflow Thread-Topic: [PATCH v7 5/6] x86/signal: Detect and prevent an alternate signal stack overflow Thread-Index: AQHXGjGh/SWJiX8oekyfIlNJ9KylvKqVEKUAgAALkICAAKhIgIAAXUOAgBuAt4A= Date: Mon, 12 Apr 2021 22:30:23 +0000 Message-ID: References: <20210316065215.23768-1-chang.seok.bae@intel.com> <20210316065215.23768-6-chang.seok.bae@intel.com> <20210325185435.GB32296@zn.tnic> <20210326103041.GB25229@zn.tnic> In-Reply-To: <20210326103041.GB25229@zn.tnic> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3608.120.23.2.4) x-originating-ip: [73.189.248.82] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 44fff02e-88ae-4231-3226-08d8fe029093 x-ms-traffictypediagnostic: PH0PR11MB4872: x-ld-processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:8273; 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charset="us-ascii" Content-ID: <0386E1260B472B48B679A4DFE8DA25E4@namprd11.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: PH0PR11MB4855.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 44fff02e-88ae-4231-3226-08d8fe029093 X-MS-Exchange-CrossTenant-originalarrivaltime: 12 Apr 2021 22:30:24.0148 (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: 5QCVppgaFrOUJhlrqLIWOK33ZV8yr0VfOF6sqEh6YHMw5IsRSwJ5J4/y/8Ov+M/PCKtlGFBHyt6yIea/wgW1Yn/LP+EbeCZXkRMvYR6OyUo= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR11MB4872 X-OriginatorOrg: intel.com X-Spam-Status: No, score=-5.3 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 12 Apr 2021 22:30:34 -0000 On Mar 26, 2021, at 03:30, Borislav Petkov wrote: > On Thu, Mar 25, 2021 at 09:56:53PM -0700, Andy Lutomirski wrote: >> We really ought to have a SIGSIGFAIL signal that's sent, double-fault >> style, when we fail to send a signal. >=20 > Yeap, we should be able to tell userspace that we couldn't send a > signal, hohumm. Hi Boris, Let me clarify some details as preparing to include this in a revision. So, IIUC, a number needs to be assigned for this new SIGFAIL. At a glance, = not sure which one to pick there in signal.h -- 1-31 fully occupied and the res= t for 33 different real-time signals. Also, perhaps, force_sig(SIGFAIL) here, instead of return -1 -- to die with SIGSEGV. Thanks, Chang