From patchwork Tue Sep 29 10:58:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 262963 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=-13.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 6AAC6C47427 for ; Tue, 29 Sep 2020 12:30:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2CDCF2083B for ; Tue, 29 Sep 2020 12:30:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601382654; bh=I5RSX6dfrllMtVP4vrgvF9MUZFSdKf2G1TCO0XX8umk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jq5kPhExhlEBEB8o50NKO+LIRt3Zn7zDpbAy0b2/VILghFdUdnj/8NdqllnAYZVas LJYcd1SeLobZJYiyOoodH3kg3AghFc0axTXZ/oCc9MMCEtnJP6M+FlVVjWXWQiDdaw gz8t/Rkuapq4cgFNm/iEjPRZsRHXZnzRNkWpmetg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732971AbgI2Maw (ORCPT ); Tue, 29 Sep 2020 08:30:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:43018 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728757AbgI2L3g (ORCPT ); Tue, 29 Sep 2020 07:29:36 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6877723A69; Tue, 29 Sep 2020 11:24:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601378642; bh=I5RSX6dfrllMtVP4vrgvF9MUZFSdKf2G1TCO0XX8umk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Eak5nXNlNDmXvpRsOABaI6j957NGyUUKqlNwham2sS9LVgYK8bA5I/Esw36iRwr4n iEpbbqZwTMSorevyGmy2lJjbid6j7OoNaF+4AyTzBOz82lc0c37tljDxXXZ/2KbLBU CupBoxH/vOPfEygaSfwcwQbjWuXV8hByA21kGRpo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alex Shi , Dave Hansen , Borislav Petkov , Sasha Levin Subject: [PATCH 4.19 087/245] x86/pkeys: Add check for pkey "overflow" Date: Tue, 29 Sep 2020 12:58:58 +0200 Message-Id: <20200929105951.227278816@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200929105946.978650816@linuxfoundation.org> References: <20200929105946.978650816@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Dave Hansen [ Upstream commit 16171bffc829272d5e6014bad48f680cb50943d9 ] Alex Shi reported the pkey macros above arch_set_user_pkey_access() to be unused. They are unused, and even refer to a nonexistent CONFIG option. But, they might have served a good use, which was to ensure that the code does not try to set values that would not fit in the PKRU register. As it stands, a too-large 'pkey' value would be likely to silently overflow the u32 new_pkru_bits. Add a check to look for overflows. Also add a comment to remind any future developer to closely examine the types used to store pkey values if arch_max_pkey() ever changes. This boots and passes the x86 pkey selftests. Reported-by: Alex Shi Signed-off-by: Dave Hansen Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20200122165346.AD4DA150@viggo.jf.intel.com Signed-off-by: Sasha Levin --- arch/x86/include/asm/pkeys.h | 5 +++++ arch/x86/kernel/fpu/xstate.c | 9 +++++++-- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h index 19b137f1b3beb..2ff9b98812b76 100644 --- a/arch/x86/include/asm/pkeys.h +++ b/arch/x86/include/asm/pkeys.h @@ -4,6 +4,11 @@ #define ARCH_DEFAULT_PKEY 0 +/* + * If more than 16 keys are ever supported, a thorough audit + * will be necessary to ensure that the types that store key + * numbers and masks have sufficient capacity. + */ #define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? 16 : 1) extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 4b900035f2202..601a5da1d196a 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -907,8 +907,6 @@ const void *get_xsave_field_ptr(int xsave_state) #ifdef CONFIG_ARCH_HAS_PKEYS -#define NR_VALID_PKRU_BITS (CONFIG_NR_PROTECTION_KEYS * 2) -#define PKRU_VALID_MASK (NR_VALID_PKRU_BITS - 1) /* * This will go out and modify PKRU register to set the access * rights for @pkey to @init_val. @@ -927,6 +925,13 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, if (!boot_cpu_has(X86_FEATURE_OSPKE)) return -EINVAL; + /* + * This code should only be called with valid 'pkey' + * values originating from in-kernel users. Complain + * if a bad value is observed. + */ + WARN_ON_ONCE(pkey >= arch_max_pkey()); + /* Set the bits we need in PKRU: */ if (init_val & PKEY_DISABLE_ACCESS) new_pkru_bits |= PKRU_AD_BIT;