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,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 ACA3BC2B9F4 for ; Mon, 14 Jun 2021 20:15:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 919FF6134F for ; Mon, 14 Jun 2021 20:15:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233510AbhFNURR (ORCPT ); Mon, 14 Jun 2021 16:17:17 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:57458 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233682AbhFNURM (ORCPT ); Mon, 14 Jun 2021 16:17:12 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1623701708; 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=GcF4L/PJ2zhQ+1ZAZQJ1sut/3O3JGVdorF5KDH2wryk=; b=bthr06o5x2i8IZjR3Haeu0ZciLSDnGUrZ7jN0bfYkWFQGNzY1myCS/VInmVTN7pRZqtV3C 9ABSDqtpIZxlv7sEfPad5c3SXMUJnBUd05FIflwqldbsReVekOn1czyQS0rz6A7iCnTgt+ znrOGeB+KMw3FwqIZQTYSnzF4S/qvQRovfsBjr0/pzCCWDA8of1FmyMPALy00UQ2EJqzx7 oNmXCfFlzyNrJsVkxdFyKSO8nfziPLauO/Abq/SfiDe4PRc1IPOjjAOQkNOBemQJWuv9mI 2XX86qgcO65+LnBjkHG1flAjRe9r4vUj8wR1FM1sdCfNHiPWK9gBh3kAUXoCTQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1623701708; 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=GcF4L/PJ2zhQ+1ZAZQJ1sut/3O3JGVdorF5KDH2wryk=; b=inhyMISw2Ofl1EV3VJbhyra2OS5jt80np7iwugxUcVGnRxzirp2tueMeGU9jQEdQzeatqz KIiDo+vZcFGWMRDw== To: LKML Cc: Andy Lutomirski , Dave Hansen , Fenghua Yu , Tony Luck , Yu-cheng Yu , Sebastian Andrzej Siewior , Borislav Petkov , Peter Zijlstra Subject: [patch] x86/fpu: x86/fpu: Preserve supervisor states in sanitize_restored_user_xstate() In-Reply-To: <20210614154408.673478623@linutronix.de> References: <20210614154408.673478623@linutronix.de> Date: Mon, 14 Jun 2021 22:15:08 +0200 Message-ID: <877diwursj.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 sanitize_restored_user_xstate() preserves the supervisor states only when the fx_only argument is zero, which allows unpriviledged user space to put supervisor states back into init state. Preserve them unconditionally. Fixes: 5d6b6a6f9b5c ("x86/fpu/xstate: Update sanitize_restored_xstate() for supervisor xstates") Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org --- arch/x86/kernel/fpu/signal.c | 26 ++++++++------------------ 1 file changed, 8 insertions(+), 18 deletions(-) --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -221,28 +221,18 @@ sanitize_restored_user_xstate(union fpre if (use_xsave()) { /* - * Note: we don't need to zero the reserved bits in the - * xstate_header here because we either didn't copy them at all, - * or we checked earlier that they aren't set. + * Clear all features bit which are not set in + * user_xfeatures and clear all extended features + * for fx_only mode. */ + u64 mask = fx_only ? XFEATURE_MASK_FPSSE : user_xfeatures; /* - * 'user_xfeatures' might have bits clear which are - * set in header->xfeatures. This represents features that - * were in init state prior to a signal delivery, and need - * to be reset back to the init state. Clear any user - * feature bits which are set in the kernel buffer to get - * them back to the init state. - * - * Supervisor state is unchanged by input from userspace. - * Ensure supervisor state bits stay set and supervisor - * state is not modified. + * Supervisor state has to be preserved. The sigframe + * restore can only modify user features, i.e. @mask + * cannot contain them. */ - if (fx_only) - header->xfeatures = XFEATURE_MASK_FPSSE; - else - header->xfeatures &= user_xfeatures | - xfeatures_mask_supervisor(); + header->xfeatures &= mask | xfeatures_mask_supervisor(); } if (use_fxsr()) {