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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 29971C4743C for ; Mon, 21 Jun 2021 16:36:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0C5F5613F0 for ; Mon, 21 Jun 2021 16:36:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231971AbhFUQit (ORCPT ); Mon, 21 Jun 2021 12:38:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:56050 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232877AbhFUQev (ORCPT ); Mon, 21 Jun 2021 12:34:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8D6BB613F6; Mon, 21 Jun 2021 16:27:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1624292835; bh=MRDSB7rhHlkBX0jrG6+LA/MMI6OOLjy29jH3CybOzAA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sVmTX1abpJiy66dAdcpHnE/MXDFe14MfjVgUoF3CfNe3ovslifSeLivIJyKhZGCKz VeUI+sP9KKr1LZAV6h+qQ0OFnGWuQOREyLLvf4v5t+XKjT/xz+5PKRsb+ObeIH51S5 BmcKO3Ufn2D2VZNqEfNccQo9mvjtWuVOClZLWGI8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Gleixner , Borislav Petkov , Dave Hansen , Rik van Riel Subject: [PATCH 5.10 119/146] x86/process: Check PF_KTHREAD and not current->mm for kernel threads Date: Mon, 21 Jun 2021 18:15:49 +0200 Message-Id: <20210621154918.937006863@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210621154911.244649123@linuxfoundation.org> References: <20210621154911.244649123@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner commit 12f7764ac61200e32c916f038bdc08f884b0b604 upstream. switch_fpu_finish() checks current->mm as indicator for kernel threads. That's wrong because kernel threads can temporarily use a mm of a user process via kthread_use_mm(). Check the task flags for PF_KTHREAD instead. Fixes: 0cecca9d03c9 ("x86/fpu: Eager switch PKRU state") Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Acked-by: Dave Hansen Acked-by: Rik van Riel Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20210608144345.912645927@linutronix.de Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/fpu/internal.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -578,7 +578,7 @@ static inline void switch_fpu_finish(str * PKRU state is switched eagerly because it needs to be valid before we * return to userland e.g. for a copy_to_user() operation. */ - if (current->mm) { + if (!(current->flags & PF_KTHREAD)) { pk = get_xsave_addr(&new_fpu->state.xsave, XFEATURE_PKRU); if (pk) pkru_val = pk->pkru;