From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6AD06C433F5 for ; Wed, 20 Oct 2021 17:45:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 57A2B6128E for ; Wed, 20 Oct 2021 17:45:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231356AbhJTRrj (ORCPT ); Wed, 20 Oct 2021 13:47:39 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:43380 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231293AbhJTRrU (ORCPT ); Wed, 20 Oct 2021 13:47:20 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]:50330) by out01.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1mdFeD-00EwJl-HB; Wed, 20 Oct 2021 11:45:05 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95]:47894 helo=localhost.localdomain) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1mdFeC-001NdN-DZ; Wed, 20 Oct 2021 11:45:05 -0600 From: "Eric W. Biederman" To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, Linus Torvalds , Oleg Nesterov , Al Viro , Kees Cook , "Eric W. Biederman" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, H Peter Anvin Date: Wed, 20 Oct 2021 12:43:56 -0500 Message-Id: <20211020174406.17889-10-ebiederm@xmission.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <87y26nmwkb.fsf@disp2133> References: <87y26nmwkb.fsf@disp2133> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-XM-SPF: eid=1mdFeC-001NdN-DZ;;;mid=<20211020174406.17889-10-ebiederm@xmission.com>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX18G2X3GZ31STtzoSfrRYAGF07hVRtRDSxY= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [PATCH 10/20] signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved. X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Instead of pretending to send SIGSEGV by calling do_exit(SIGSEGV) call force_sigsegv(SIGSEGV) to force the process to take a SIGSEGV and terminate. Update handle_signal to return immediately when save_v86_state fails and kills the process. Returning immediately without doing anything except killing the process with SIGSEGV is also what signal_setup_done does when setup_rt_frame fails. Plus it is always ok to return immediately without delivering a signal to a userspace handler when a fatal signal has killed the current process. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: x86@kernel.org Cc: H Peter Anvin Signed-off-by: "Eric W. Biederman" --- arch/x86/kernel/signal.c | 6 +++++- arch/x86/kernel/vm86_32.c | 2 +- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index f4d21e470083..25a230f705c1 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -785,8 +785,12 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs) bool stepping, failed; struct fpu *fpu = ¤t->thread.fpu; - if (v8086_mode(regs)) + if (v8086_mode(regs)) { save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL); + /* Has save_v86_state failed and killed the process? */ + if (fatal_signal_pending(current)) + return; + } /* Are we from a system call? */ if (syscall_get_nr(current, regs) != -1) { diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c index 63486da77272..040fd01be8b3 100644 --- a/arch/x86/kernel/vm86_32.c +++ b/arch/x86/kernel/vm86_32.c @@ -159,7 +159,7 @@ void save_v86_state(struct kernel_vm86_regs *regs, int retval) user_access_end(); Efault: pr_alert("could not access userspace vm86 info\n"); - do_exit(SIGSEGV); + force_sigsegv(SIGSEGV); } static int do_vm86_irq_handling(int subfunction, int irqnumber); -- 2.20.1