Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933681AbbDWKSx (ORCPT ); Thu, 23 Apr 2015 06:18:53 -0400 Received: from mail.skyhub.de ([78.46.96.112]:50269 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932453AbbDWKSu (ORCPT ); Thu, 23 Apr 2015 06:18:50 -0400 Date: Thu, 23 Apr 2015 12:18:40 +0200 From: Borislav Petkov To: Denys Vlasenko Cc: Andy Lutomirski , Brian Gerst , Steven Rostedt , Oleg Nesterov , Ingo Molnar , "H. Peter Anvin" , Linus Torvalds , Andy Lutomirski , Will Drewry , =?utf-8?B?RnLDqWTDqXJpYw==?= Weisbecker , Alexei Starovoitov , Linux Kernel Mailing List , Kees Cook , Thomas Gleixner , "linux-tip-commits@vger.kernel.org" Subject: Re: [tip:x86/vdso] x86/vdso32/syscall.S: Do not load __USER32_DS to %ss Message-ID: <20150423101840.GC28327@pd.tnic> References: <63da6d778f69fd0f1345d9287f6764d58be519fa.1427482099.git.luto@kernel.org> <5538C1C5.7010408@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <5538C1C5.7010408@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 984 Lines: 31 On Thu, Apr 23, 2015 at 11:56:21AM +0200, Denys Vlasenko wrote: > The fix can look like this (untested): > > > diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S > index 0c302d0..9f4c232 100644 > --- a/arch/x86/ia32/ia32entry.S > +++ b/arch/x86/ia32/ia32entry.S > @@ -198,6 +198,18 @@ sysexit_from_sys_call: > * with 'sysenter' and it uses the SYSENTER calling convention. > */ > andl $~TS_COMPAT,ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) > + /* > + * On AMD, SYSRET32 does not modify %ss cached descriptor; Ok, but doc says that in both long and compat mode, SYSRET does load SS.sel with the value in MSR_STAR... Hmmm. -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/