From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753836AbcKPRym (ORCPT ); Wed, 16 Nov 2016 12:54:42 -0500 Received: from mx2.suse.de ([195.135.220.15]:56412 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752312AbcKPRyl (ORCPT ); Wed, 16 Nov 2016 12:54:41 -0500 Date: Wed, 16 Nov 2016 18:54:37 +0100 From: Borislav Petkov To: Yu-cheng Yu Cc: linux-kernel@vger.kernel.org, x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Andy Lutomirski , David Hansen , Fenghua Yu , "Ravi V. Shankar" Subject: Re: [PATCH] x86/fpu: Fix invalid FPU ptrace state after execve Message-ID: <20161116175437.wfph6ee5zmsyzqwz@pd.tnic> References: <1479315396-2131-1-git-send-email-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1479315396-2131-1-git-send-email-yu-cheng.yu@intel.com> User-Agent: NeoMutt/20161014 (1.7.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 16, 2016 at 08:56:36AM -0800, Yu-cheng Yu wrote: > Robert O'Callahan reported that after an execve PTRACE_GETREGSET > NT_X86_XSTATE continues to return the pre-exec register values > until the exec'ed task modifies FPU state. The test code is at > https://bugzilla.redhat.com/attachment.cgi?id=1164286. > > What is happening is when eagerfpu is enabled, fpu__clear() did > not properly clear fpstate. Fix it by doing just that. > > Signed-off-by: Yu-cheng Yu > Reported-by: Robert O'Callahan > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: "H. Peter Anvin" > Cc: Andy Lutomirski > Cc: Borislav Petkov > Cc: David Hansen > Cc: Fenghua Yu > Cc: "Ravi V. Shankar" > --- > arch/x86/kernel/fpu/core.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c > index 4700401..4c203c4 100644 > --- a/arch/x86/kernel/fpu/core.c > +++ b/arch/x86/kernel/fpu/core.c > @@ -521,14 +521,14 @@ void fpu__clear(struct fpu *fpu) > { > WARN_ON_FPU(fpu != ¤t->thread.fpu); /* Almost certainly an anomaly */ > > - if (!use_eager_fpu() || !static_cpu_has(X86_FEATURE_FPU)) { > - /* FPU state will be reallocated lazily at the first use. */ > - fpu__drop(fpu); > - } else { > - if (!fpu->fpstate_active) { > - fpu__activate_curr(fpu); > - user_fpu_begin(); > - } > + fpu__drop(fpu); > + > + /* > + * When eagerfpu is used, make sure fpstate is cleared and initialized. > + */ > + if (use_eager_fpu()) { c592b5734706 ("x86/fpu: Remove use_eager_fpu()") Please redo this patch against tip/master. -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --