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=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 6AA42C43464 for ; Fri, 18 Sep 2020 03:06:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C9CD21582 for ; Fri, 18 Sep 2020 03:06:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600398416; bh=16tazY5VJe08ylA+XFDUXd9D+yYNp9RB/kAuN2PirUA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JlqF9Isql+nKEsiCLqpOLUeNwzXOfo2Ed9iikw/rXZwh6Y1TPjSg8BWUwvYEKhz/y M1aDULZUceCAJsHRdTLPqA1lejDk7Vs1GUwby2oG2gfqbRX+IYwSGty3P6OtDGjCpb Yqizul+Mz/6fqCAXJDZnesmOkeTDjG4iM6E81vik= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728745AbgIRDGy (ORCPT ); Thu, 17 Sep 2020 23:06:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:50888 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727196AbgIRCEB (ORCPT ); Thu, 17 Sep 2020 22:04:01 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C199A235FD; Fri, 18 Sep 2020 02:03:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600394639; bh=16tazY5VJe08ylA+XFDUXd9D+yYNp9RB/kAuN2PirUA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=apEpPylLy3NJSCSRZ2OmPijoi4wUhfPSJLSz36IYwrLsxehPJVv6APxL9VWIRmJWX +QtfDUJBAVMC49t+5EKISdPLI3jU0LNckzgsg8+7O97mdxO2rKFlb4tHZSnCtvcQng fO/m20l6ghdI85t2Z6e1brz28KlhrG8UzSnNcNfs= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Dave Hansen , Alex Shi , Dave Hansen , Borislav Petkov , Sasha Levin Subject: [PATCH AUTOSEL 5.4 138/330] x86/pkeys: Add check for pkey "overflow" Date: Thu, 17 Sep 2020 21:57:58 -0400 Message-Id: <20200918020110.2063155-138-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918020110.2063155-1-sashal@kernel.org> References: <20200918020110.2063155-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 755eb26cbec04..735d1f1bbabc7 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -895,8 +895,6 @@ const void *get_xsave_field_ptr(int xfeature_nr) #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. @@ -915,6 +913,13 @@ 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; -- 2.25.1