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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EEDEFC433EF for ; Thu, 14 Jul 2022 04:04:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231357AbiGNEEV (ORCPT ); Thu, 14 Jul 2022 00:04:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229473AbiGNEES (ORCPT ); Thu, 14 Jul 2022 00:04:18 -0400 Received: from mail-lf1-x129.google.com (mail-lf1-x129.google.com [IPv6:2a00:1450:4864:20::129]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CEC87275D5 for ; Wed, 13 Jul 2022 21:04:16 -0700 (PDT) Received: by mail-lf1-x129.google.com with SMTP id r9so798211lfp.10 for ; Wed, 13 Jul 2022 21:04:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=4i9kRRQ3z5mPuTkc7JYERdBNQjh9yJap1kHoFmvgt2E=; b=g2PW9IgWmqtqJqypCXqUQuEht8KkrnXHuWybS7uFFKnrHx34x8vzi8X43eSz5cpPvb RU/lfqVHLQeGjNLX+ryurrcn/yPW2Egl7H1MeSeBYtzdnBlokD6W8RARKfcKjb9mSx2H 73RILF0jFfUKLuF5FGMhd/OPwnIQec9eVD6fhIDBujAhXWjaF5ZVDEeTPRM+RA38lta3 CbfBbR/LhkV9aRqfo/bpb1VYmQ9eVtfovKyQyDNp7caDWiQ3yYWEWfAhEXDkD6YtU9A5 pLCJ+nf7Q4Lkw0BBYMPFL17FB3rM8R7NuiMeiczNU9IqB6vxc/9VD2zVKLa4ehJ9vxwo PvKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=4i9kRRQ3z5mPuTkc7JYERdBNQjh9yJap1kHoFmvgt2E=; b=hw2SmBzplYMqFTQ04L6nJK4otYPgmuFsE4GjWQW8jGLDTCsvWwLjQojO1rsB4T1PQh 2z4iFzCqy7+ixdLu6dI75p8B7mdghxMp8S552heUSeoiLN0+//YFJQJMc5VzwdmExzne gw4z+/LcmRsrNRLsGuwB+BepT4wF13aLyLhFdlT0W++K4rFZZwYo4YOYhuClgO4hU1rs BypjJuz7iw7lzmixJGfGD119IouIj25ZNA93fKKVZzRZH7w1GZGaO9uu41QTBrrRImA0 lyxEMliDDa/IGBtuIRGNvl2NSwQCrrgS5pRbUx0+nUpyihZnHyP3jFtXoNj0WjmejaRa Wn8g== X-Gm-Message-State: AJIora/lR/C0aJ4Ue5n3TTKddWNsHZBOb4wf4mK0l3jeVAmR/XNg3VWo NCAnWDlKIMALNpVsRsYiqkb3+4X61Ie85wC7XRA= X-Google-Smtp-Source: AGRyM1tTXHqt4pCwxoPjOyqf/dZLan2X/Xhis7R50nAsZuWfR4YjfA9pDssH6EMEMRpQ9gggAzyTiGViJC6Jx2ikHYU= X-Received: by 2002:a05:6512:23aa:b0:489:ddb4:6f84 with SMTP id c42-20020a05651223aa00b00489ddb46f84mr3923640lfv.683.1657771454853; Wed, 13 Jul 2022 21:04:14 -0700 (PDT) MIME-Version: 1.0 References: <20210623120127.327154589@linutronix.de> <20210623121452.214903673@linutronix.de> In-Reply-To: <20210623121452.214903673@linutronix.de> From: Andrei Vagin Date: Wed, 13 Jul 2022 21:04:02 -0700 Message-ID: Subject: Re: [patch V4 09/65] x86/fpu: Sanitize xstateregs_set() To: Thomas Gleixner Cc: LKML , Andy Lutomirski , Dave Hansen , Fenghua Yu , Tony Luck , Yu-cheng Yu , Sebastian Andrzej Siewior , Borislav Petkov , Peter Zijlstra , Kan Liang , Chang Seok Bae , Megha Dey , Oliver Sang Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 23, 2021 at 5:24 AM Thomas Gleixner wrote: .... > > - /* > - * mxcsr reserved bits must be masked to zero for security reasons. > - */ > - xsave->i387.mxcsr &= mxcsr_feature_mask; > - > - /* > - * In case of failure, mark all states as init: > - */ > - if (ret) > - fpstate_init(&fpu->state); > + fpu__prepare_write(fpu); > + ret = copy_kernel_to_xstate(&fpu->state.xsave, kbuf ?: tmpbuf); This change breaks gVisor. Now, when we set a new fpu state without fp,sse and ymm via ptrace, mxcsr isn't reset to the default value. The issue is reproduced only on hosts without xsaves. On hosts with xsaves, it works as expected. Thanks, Andrei