From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757298AbXFWA3y (ORCPT ); Fri, 22 Jun 2007 20:29:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753082AbXFWA3f (ORCPT ); Fri, 22 Jun 2007 20:29:35 -0400 Received: from ns2.suse.de ([195.135.220.15]:53618 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752565AbXFWA3e (ORCPT ); Fri, 22 Jun 2007 20:29:34 -0400 From: Andi Kleen References: <20070623229.766711000@suse.de> In-Reply-To: <20070623229.766711000@suse.de> To: jbeulich@novell.com, patches@x86-64.org, torvalds@osdl.org, linux-kernel@vger.kernel.org Subject: [PATCH for 2.6.22] [3/3] x86_64: Ignore compat mode SYSCALL when IA32_EMULATION is not defined Message-Id: <20070623002925.EED7414B35@wotan.suse.de> Date: Sat, 23 Jun 2007 02:29:25 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Previously a program could switch to a compat mode segment and then execute SYSCALL and it would jump to an uninitialized MSR and crash the kernel. Instead supply a dummy target for this case. Pointed out by Jan Beulich Cc: jbeulich@novell.com Signed-off-by: Andi Kleen --- arch/x86_64/kernel/entry.S | 7 +++++++ arch/x86_64/kernel/setup64.c | 3 +++ 2 files changed, 10 insertions(+) Index: linux/arch/x86_64/kernel/entry.S =================================================================== --- linux.orig/arch/x86_64/kernel/entry.S +++ linux/arch/x86_64/kernel/entry.S @@ -1163,3 +1163,10 @@ ENTRY(call_softirq) ret CFI_ENDPROC ENDPROC(call_softirq) + +KPROBE_ENTRY(ignore_sysret) + CFI_STARTPROC + mov $-ENOSYS,%eax + sysret + CFI_ENDPROC +ENDPROC(ignore_sysret) Index: linux/arch/x86_64/kernel/setup64.c =================================================================== --- linux.orig/arch/x86_64/kernel/setup64.c +++ linux/arch/x86_64/kernel/setup64.c @@ -150,6 +150,8 @@ void pda_init(int cpu) char boot_exception_stacks[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ] __attribute__((section(".bss.page_aligned"))); +extern asmlinkage void ignore_sysret(void); + /* May not be marked __init: used by software suspend */ void syscall_init(void) { @@ -160,6 +162,7 @@ void syscall_init(void) */ wrmsrl(MSR_STAR, ((u64)__USER32_CS)<<48 | ((u64)__KERNEL_CS)<<32); wrmsrl(MSR_LSTAR, system_call); + wrmsrl(MSR_CSTAR, ignore_sysret); #ifdef CONFIG_IA32_EMULATION syscall32_cpu_init ();