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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 73F81C48BC2 for ; Mon, 21 Jun 2021 10:17:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DC416100B for ; Mon, 21 Jun 2021 10:17:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230269AbhFUKUA (ORCPT ); Mon, 21 Jun 2021 06:20:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57710 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229621AbhFUKT7 (ORCPT ); Mon, 21 Jun 2021 06:19:59 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 196A0C061574 for ; Mon, 21 Jun 2021 03:17:45 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1624270663; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qft33V4n9w3liTUGyYv8UgJkn2C6rbIC2OAf9sOGNjk=; b=zlvyGNzuMG71JDurWdOkedBk2iDwGJsC1+60MfER/DwqGFsRwO7WRvoX+vcg96W+5OCQEl tU1E2lAidXhunOG9zbosY6v59HEGFFw6RyLYA8eDvB6m/2KFZNU+/CCh2kWnW2Gh+lxrAw JPlffgwg2QDm4uBGTpC0yDZBZ3hqH77fCq/ItaBhA/6wUlrWuy8xML3XOlSkcuSW7aUjig d6Wk8zIWnaoU2hhRSQKw3b1xLyBsLJ1VURezSoK3axyngKaEFCviurZSXomrn9GwAeS9e+ EEj5m7oUoROdgTOIgrLsNiymPROxHl3vE4/vieEZRok812Yt8dmgZ/ZLek4YhA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1624270663; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qft33V4n9w3liTUGyYv8UgJkn2C6rbIC2OAf9sOGNjk=; b=YPhOey8KYJ06wNQYMWravZAmAiWNwIXTQzt5oAB9StScGwNsTWs+1c0pV2GTmK9K1ifUQV xmQ5Ew3q5L6pHNDw== To: LKML Cc: Andy Lutomirski , Dave Hansen , Fenghua Yu , Tony Luck , Yu-cheng Yu , Sebastian Andrzej Siewior , Borislav Petkov , Peter Zijlstra , Kan Liang Subject: Re: [patch V3 15/66] x86/fpu: Fail ptrace() requests that try to set invalid MXCSR values In-Reply-To: <20210618143446.088319013@linutronix.de> References: <20210618141823.161158090@linutronix.de> <20210618143446.088319013@linutronix.de> Date: Mon, 21 Jun 2021 12:17:43 +0200 Message-ID: <87mtrjfrnc.ffs@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 18 2021 at 16:18, Thomas Gleixner wrote: > From: Andy Lutomirski > > There is no benefit from accepting and silently changing an invalid MXCSR > value supplied via ptrace(). Instead, return -EINVAL on invalid input. > > Signed-off-by: Andy Lutomirski > Signed-off-by: Thomas Gleixner > --- > V2: New patch. Picked up from Andy. > --- > arch/x86/kernel/fpu/regset.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > --- > --- a/arch/x86/kernel/fpu/regset.c > +++ b/arch/x86/kernel/fpu/regset.c > @@ -64,8 +64,9 @@ int xfpregs_set(struct task_struct *targ > if (ret) > return ret; > > - /* Mask invalid MXCSR bits (for historical reasons). */ > - newstate.mxcsr &= mxcsr_feature_mask; > + /* Do not allow an invalid MXCSR value. */ > + if (newstate.mxcsr & ~mxcsr_feature_mask) > + ret = -EINVAL; This obviously needs to be: return -EINVAL; /me goes to find a brown paperbag