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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9024AC4743C for ; Mon, 14 Jun 2021 16:38:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7AABB613D0 for ; Mon, 14 Jun 2021 16:38:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234955AbhFNQkg (ORCPT ); Mon, 14 Jun 2021 12:40:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234789AbhFNQkE (ORCPT ); Mon, 14 Jun 2021 12:40:04 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95B06C061574 for ; Mon, 14 Jun 2021 09:38:01 -0700 (PDT) Message-Id: <20210614155354.935915316@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1623688680; 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: content-transfer-encoding:content-transfer-encoding: references:references; bh=QEpaw02U7+Qp+O5kTJbVqJSDsevvpgnJvGsvNmpTKDE=; b=elB7lDCTIPMDd8y7sPeY6nk50hVhtfeJr46B0rEZ9lvlWpkPz/8B2CLq02GVfN+Ee17usW 7trWvXkegZBRzDuntzZlmsx8DkOUOgEuMRZSHCkq1c9n5NERUsI09JXSeg8L5yADnWvEno P5dJBIOQga37LjBxVOYdQ2MKqudyECyzKOVuChVc5mVrIDkfaea1T2pIfB0+NA++Wf74go qSaAlP9PladA+1B/gfzcvFa217CbMMVM548ehIoYj2YXHk7NlwmW2+vPF41XDaNN0nUw04 R2C30k2wsWjajOfsQuROR8UabqoIedhFrE/iqwh5IJeYfF9bNDyPZ5NvT2u2KA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1623688680; 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: content-transfer-encoding:content-transfer-encoding: references:references; bh=QEpaw02U7+Qp+O5kTJbVqJSDsevvpgnJvGsvNmpTKDE=; b=KxFcBbBZRhnB3H6TRFuPDwSh7oFPz9T8BglpgKIx9xUQtGlcVOuA6A9G4xqJXz3X1XQ7Ps GbDwG8qxnEKZVpAg== Date: Mon, 14 Jun 2021 17:44:20 +0200 From: Thomas Gleixner To: LKML Cc: Andy Lutomirski , Dave Hansen , Fenghua Yu , Tony Luck , Yu-cheng Yu , Sebastian Andrzej Siewior , Borislav Petkov , Peter Zijlstra , Kan Liang Subject: [patch V2 12/52] x86/fpu: Fail ptrace() requests that try to set invalid MXCSR values References: <20210614154408.673478623@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andy Lutomirski We're not doing anyone any favors by accepting and silently changing an invalid MXCSR value supplied via ptrace(). Instead, return -EINVAL on invalid input. If this breaks something, we can revert it. 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 @@ -65,8 +65,9 @@ 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; fpu__prepare_write(fpu);