Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965295AbdLVJEz (ORCPT ); Fri, 22 Dec 2017 04:04:55 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:40618 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934003AbdLVJE3 (ORCPT ); Fri, 22 Dec 2017 04:04:29 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski , Thomas Gleixner , Borislav Petkov , Boris Ostrovsky , Borislav Petkov , Borislav Petkov , Brian Gerst , Dave Hansen , Dave Hansen , David Laight , Denys Vlasenko , Eduardo Valentin , "H. Peter Anvin" , Josh Poimboeuf , Juergen Gross , Linus Torvalds , Peter Zijlstra , Rik van Riel , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Ingo Molnar Subject: [PATCH 4.14 094/159] x86/entry/64: Remove the SYSENTER stack canary Date: Fri, 22 Dec 2017 09:46:19 +0100 Message-Id: <20171222084628.825378877@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171222084623.668990192@linuxfoundation.org> References: <20171222084623.668990192@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3263 Lines: 96 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Lutomirski commit 7fbbd5cbebf118a9e09f5453f686656a167c3d1c upstream. Now that the SYSENTER stack has a guard page, there's no need for a canary to detect overflow after the fact. Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Reviewed-by: Thomas Gleixner Reviewed-by: Borislav Petkov Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Dave Hansen Cc: David Laight Cc: Denys Vlasenko Cc: Eduardo Valentin Cc: Greg KH Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Rik van Riel Cc: Will Deacon Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Link: https://lkml.kernel.org/r/20171204150606.572577316@linutronix.de Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/processor.h | 1 - arch/x86/kernel/dumpstack.c | 3 +-- arch/x86/kernel/process.c | 1 - arch/x86/kernel/traps.c | 7 ------- 4 files changed, 1 insertion(+), 11 deletions(-) --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -341,7 +341,6 @@ struct tss_struct { * Space for the temporary SYSENTER stack, used for SYSENTER * and the entry trampoline as well. */ - unsigned long SYSENTER_stack_canary; unsigned long SYSENTER_stack[64]; /* --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -48,8 +48,7 @@ bool in_sysenter_stack(unsigned long *st int cpu = smp_processor_id(); struct tss_struct *tss = &get_cpu_entry_area(cpu)->tss; - /* Treat the canary as part of the stack for unwinding purposes. */ - void *begin = &tss->SYSENTER_stack_canary; + void *begin = &tss->SYSENTER_stack; void *end = (void *)&tss->SYSENTER_stack + sizeof(tss->SYSENTER_stack); if ((void *)stack < begin || (void *)stack >= end) --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -81,7 +81,6 @@ __visible DEFINE_PER_CPU_SHARED_ALIGNED( */ .io_bitmap = { [0 ... IO_BITMAP_LONGS] = ~0 }, #endif - .SYSENTER_stack_canary = STACK_END_MAGIC, }; EXPORT_PER_CPU_SYMBOL(cpu_tss); --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -814,13 +814,6 @@ dotraplinkage void do_debug(struct pt_re debug_stack_usage_dec(); exit: - /* - * This is the most likely code path that involves non-trivial use - * of the SYSENTER stack. Check that we haven't overrun it. - */ - WARN(this_cpu_read(cpu_tss.SYSENTER_stack_canary) != STACK_END_MAGIC, - "Overran or corrupted SYSENTER stack\n"); - ist_exit(regs); } NOKPROBE_SYMBOL(do_debug);