From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-dm3nam03on0129.outbound.protection.outlook.com ([104.47.41.129]:29327 "EHLO NAM03-DM3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S967057AbeCSQPF (ORCPT ); Mon, 19 Mar 2018 12:15:05 -0400 From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: "Eric W. Biederman" , Russell King , "linux-arm-kernel@lists.infradead.org" , Sasha Levin Subject: [PATCH AUTOSEL for 3.18 102/102] signal/arm: Document conflicts with SI_USER and SIGFPE Date: Mon, 19 Mar 2018 16:13:41 +0000 Message-ID: <20180319161117.17833-102-alexander.levin@microsoft.com> References: <20180319161117.17833-1-alexander.levin@microsoft.com> In-Reply-To: <20180319161117.17833-1-alexander.levin@microsoft.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: From: "Eric W. Biederman" [ Upstream commit 7771c66457004977b616bab785209f49d164f527 ] 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 be reliably copied. 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: Russell King Cc: linux-arm-kernel@lists.infradead.org Ref: 451436b7bbb2 ("[ARM] Add support code for ARM hardware vector floating= point") History 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/arm/include/uapi/asm/siginfo.h | 13 +++++++++++++ arch/arm/vfp/vfpmodule.c | 2 +- 2 files changed, 14 insertions(+), 1 deletion(-) create mode 100644 arch/arm/include/uapi/asm/siginfo.h diff --git a/arch/arm/include/uapi/asm/siginfo.h b/arch/arm/include/uapi/as= m/siginfo.h new file mode 100644 index 000000000000..d0513880be21 --- /dev/null +++ b/arch/arm/include/uapi/asm/siginfo.h @@ -0,0 +1,13 @@ +#ifndef __ASM_SIGINFO_H +#define __ASM_SIGINFO_H + +#include + +/* + * SIGFPE si_codes + */ +#ifdef __KERNEL__ +#define FPE_FIXME 0 /* Broken dup of SI_USER */ +#endif /* __KERNEL__ */ + +#endif diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index 2f37e1d6cb45..b646400bfb0e 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -261,7 +261,7 @@ static void vfp_raise_exceptions(u32 exceptions, u32 in= st, u32 fpscr, struct pt_ =20 if (exceptions =3D=3D VFP_EXCEPTION_ERROR) { vfp_panic("unhandled bounce", inst); - vfp_raise_sigfpe(0, regs); + vfp_raise_sigfpe(FPE_FIXME, regs); return; } =20 --=20 2.14.1