From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: [PATCH AUTOSEL for 4.15 118/124] signal/parisc: Document a conflict with SI_USER with SIGFPE Date: Mon, 19 Mar 2018 15:49:14 +0000 Message-ID: <20180319154645.11350-118-alexander.levin@microsoft.com> References: <20180319154645.11350-1-alexander.levin@microsoft.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Cc: "Eric W. Biederman" , "James E.J. Bottomley" , Helge Deller , "linux-parisc@vger.kernel.org" , Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Return-path: In-Reply-To: <20180319154645.11350-1-alexander.levin@microsoft.com> List-ID: From: "Eric W. Biederman" [ Upstream commit b5daf2b9d1c9a2b4f03ca93f75913ba2da3b3eaa ] Setting si_code to 0 results in a userspace seeing an si_code of 0. This is the same si_code as SI_USER. Posix and common sense requires that SI_USER not be a signal specific si_code. As such this use of 0 for the si_code is a pretty horribly broken ABI. Further use of si_code =3D=3D 0 guaranteed that copy_siginfo_to_user saw a value of __SI_KILL and now sees a value of SIL_KILL with the result that uid and pid fields are copied and which might copying the si_addr field by accident but certainly not by design. Making this a very flakey implementation. Utilizing FPE_FIXME siginfo_layout will now return SIL_FAULT and the appropriate fields will reliably be copied. This bug is 13 years old and parsic machines are no longer being built so I don't know if it possible or worth fixing it. But it is at least worth documenting this so other architectures don't make the same mistake. Possible ABI fixes includee: - Send the signal without siginfo - Don't generate a signal - Possibly assign and use an appropriate si_code - Don't handle cases which can't happen Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: linux-parisc@vger.kernel.org Ref: 313c01d3e3fd ("[PATCH] PA-RISC update for 2.6.0") Histroy Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.= git Signed-off-by: "Eric W. Biederman" Signed-off-by: Sasha Levin --- arch/parisc/include/uapi/asm/siginfo.h | 7 +++++++ arch/parisc/kernel/traps.c | 2 +- 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/parisc/include/uapi/asm/siginfo.h b/arch/parisc/include/u= api/asm/siginfo.h index 4a1062e05aaf..be40331f757d 100644 --- a/arch/parisc/include/uapi/asm/siginfo.h +++ b/arch/parisc/include/uapi/asm/siginfo.h @@ -8,4 +8,11 @@ =20 #include =20 +/* + * SIGFPE si_codes + */ +#ifdef __KERNEL__ +#define FPE_FIXME 0 /* Broken dup of SI_USER */ +#endif /* __KERNEL__ */ + #endif diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c index 8453724b8009..c919e6c0a687 100644 --- a/arch/parisc/kernel/traps.c +++ b/arch/parisc/kernel/traps.c @@ -629,7 +629,7 @@ void notrace handle_interruption(int code, struct pt_re= gs *regs) si.si_signo =3D SIGFPE; /* Set to zero, and let the userspace app figure it out from the insn pointed to by si_addr */ - si.si_code =3D 0; + si.si_code =3D FPE_FIXME; si.si_addr =3D (void __user *) regs->iaoq[0]; 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Biederman" , "James E.J. Bottomley" , Helge Deller , "linux-parisc@vger.kernel.org" , Sasha Levin Subject: [PATCH AUTOSEL for 4.15 118/124] signal/parisc: Document a conflict with SI_USER with SIGFPE Thread-Topic: [PATCH AUTOSEL for 4.15 118/124] signal/parisc: Document a conflict with SI_USER with SIGFPE Thread-Index: AQHTv5nU1jM4TEEmbE2qukzwpEcuig== Date: Mon, 19 Mar 2018 15:49:14 +0000 Message-ID: <20180319154645.11350-118-alexander.levin@microsoft.com> References: <20180319154645.11350-1-alexander.levin@microsoft.com> In-Reply-To: <20180319154645.11350-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB1109;7:w+hE0tQMAg4HJBBV3c/IqoZUZaK/NpMAp5+m3uZMTHzYNRibmpK83J1yYzUd22mki6c6MmPPzrvt9GmZsp7AngVnWr0lBSMVRbidzAliGV2rtfgqca3o+664cCUj+udS7zI7SdC3pwx5iykGTjwZiDoV37I+StQSHqUhEIrb5BuvhiAMuPPfqhg8HRCNuQPK5Nkq4k+6WO4Iuamd9vqo95VBjV+ZmPmcYqm6pilZdWoMsiTljwCjvMbXK1mBt4mX;20:6/r/2oXNpD/otaGLVcpnbF8uKHZ7XtKDXBoRHcXU9CckkAL5eTd95CngGdNBxltwbK2FQKfP5aNtfdEnW84w/fo0UmDN9bjL+x42ew1ip7bpdSfo/ZaSq8HcB1m9a4dsa7cys/rfd/BdmgI4vEahOOMzDia9MhbZ+XR+XGT9Bx8= x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 55fa054a-03d0-46ec-1a36-08d58db11623 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB1109; x-ms-traffictypediagnostic: DM5PR2101MB1109: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alexander.Levin@microsoft.com; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(28532068793085)(26323138287068)(89211679590171)(9452136761055)(84791874153150); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(61425038)(6040522)(2401047)(5005006)(8121501046)(3231221)(944501300)(52105095)(3002001)(93006095)(93001095)(10201501046)(6055026)(61426038)(61427038)(6041310)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123560045)(20161123562045)(20161123564045)(20161123558120)(6072148)(201708071742011);SRVR:DM5PR2101MB1109;BCL:0;PCL:0;RULEID:;SRVR:DM5PR2101MB1109; x-forefront-prvs: 06167FAD59 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(366004)(396003)(39860400002)(39380400002)(376002)(346002)(199004)(189003)(81166006)(10290500003)(107886003)(81156014)(106356001)(6506007)(8676002)(3846002)(36756003)(8936002)(97736004)(6116002)(1076002)(102836004)(68736007)(6666003)(3280700002)(2950100002)(3660700001)(478600001)(72206003)(59450400001)(2906002)(14454004)(966005)(76176011)(66066001)(8666007)(6512007)(6306002)(5250100002)(10090500001)(2501003)(53936002)(6486002)(6436002)(26005)(316002)(22452003)(305945005)(7736002)(4326008)(25786009)(86362001)(575784001)(86612001)(5660300001)(2900100001)(99286004)(54906003)(186003)(105586002)(110136005)(22906009)(217873001);DIR:OUT;SFP:1102;SCL:1;SRVR:DM5PR2101MB1109;H:DM5PR2101MB1032.namprd21.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; x-microsoft-antispam-message-info: nA6/g/HVO/zpIK/6UreIEVSNbSgnXnFrDCzZkD4LqunojCkO8ErZvUQ2MpB2a1v3x7SkSXIPs9UVHaws7Pja8WGynGTdLa7iL6OTW8TDfQVD3TLAo5JsHwIkNBefi2tMfw+bQdjeu36E20arN6Z/O6Rhvv+xBTc8Qjt39yYdhlNJYobmHedfh9buUut3H+3PKT7w4uNM7ro5WKc8JGJERn80p9f2miY1Df0CrohArrcWEIBiRYjZ6xu97tvxaCqSge+aYrizfA0orKtH1F5J5SWcg2g2PfeNhMt3kDl301jagnv4kqTmcQNNlkgkQ7vYiWQaLW23785mmYTSQKxp+w== spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 55fa054a-03d0-46ec-1a36-08d58db11623 X-MS-Exchange-CrossTenant-originalarrivaltime: 19 Mar 2018 15:49:14.4447 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1109 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: "Eric W. Biederman" [ Upstream commit b5daf2b9d1c9a2b4f03ca93f75913ba2da3b3eaa ] Setting si_code to 0 results in a userspace seeing an si_code of 0. This is the same si_code as SI_USER. Posix and common sense requires that SI_USER not be a signal specific si_code. As such this use of 0 for the si_code is a pretty horribly broken ABI. Further use of si_code =3D=3D 0 guaranteed that copy_siginfo_to_user saw a value of __SI_KILL and now sees a value of SIL_KILL with the result that uid and pid fields are copied and which might copying the si_addr field by accident but certainly not by design. Making this a very flakey implementation. Utilizing FPE_FIXME siginfo_layout will now return SIL_FAULT and the appropriate fields will reliably be copied. This bug is 13 years old and parsic machines are no longer being built so I don't know if it possible or worth fixing it. But it is at least worth documenting this so other architectures don't make the same mistake. Possible ABI fixes includee: - Send the signal without siginfo - Don't generate a signal - Possibly assign and use an appropriate si_code - Don't handle cases which can't happen Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: linux-parisc@vger.kernel.org Ref: 313c01d3e3fd ("[PATCH] PA-RISC update for 2.6.0") Histroy Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.= git Signed-off-by: "Eric W. Biederman" Signed-off-by: Sasha Levin --- arch/parisc/include/uapi/asm/siginfo.h | 7 +++++++ arch/parisc/kernel/traps.c | 2 +- 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/parisc/include/uapi/asm/siginfo.h b/arch/parisc/include/u= api/asm/siginfo.h index 4a1062e05aaf..be40331f757d 100644 --- a/arch/parisc/include/uapi/asm/siginfo.h +++ b/arch/parisc/include/uapi/asm/siginfo.h @@ -8,4 +8,11 @@ =20 #include =20 +/* + * SIGFPE si_codes + */ +#ifdef __KERNEL__ +#define FPE_FIXME 0 /* Broken dup of SI_USER */ +#endif /* __KERNEL__ */ + #endif diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c index 8453724b8009..c919e6c0a687 100644 --- a/arch/parisc/kernel/traps.c +++ b/arch/parisc/kernel/traps.c @@ -629,7 +629,7 @@ void notrace handle_interruption(int code, struct pt_re= gs *regs) si.si_signo =3D SIGFPE; /* Set to zero, and let the userspace app figure it out from the insn pointed to by si_addr */ - si.si_code =3D 0; + si.si_code =3D FPE_FIXME; si.si_addr =3D (void __user *) regs->iaoq[0]; force_sig_info(SIGFPE, &si, current); return; --=20 2.14.1