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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 53133ECDFB8 for ; Fri, 20 Jul 2018 05:10:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D65220850 for ; Fri, 20 Jul 2018 05:10:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0D65220850 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727359AbeGTF4u (ORCPT ); Fri, 20 Jul 2018 01:56:50 -0400 Received: from terminus.zytor.com ([198.137.202.136]:43709 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726415AbeGTF4u (ORCPT ); Fri, 20 Jul 2018 01:56:50 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w6K5ALAj2538379 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Thu, 19 Jul 2018 22:10:21 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w6K5ALV52538376; Thu, 19 Jul 2018 22:10:21 -0700 Date: Thu, 19 Jul 2018 22:10:21 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Jiang Biao Message-ID: Cc: mingo@kernel.org, hpa@zytor.com, tglx@linutronix.de, linux-kernel@vger.kernel.org, jiang.biao2@zte.com.cn Reply-To: linux-kernel@vger.kernel.org, jiang.biao2@zte.com.cn, hpa@zytor.com, mingo@kernel.org, tglx@linutronix.de In-Reply-To: <1532045192-49622-2-git-send-email-jiang.biao2@zte.com.cn> References: <1532045192-49622-2-git-send-email-jiang.biao2@zte.com.cn> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/pti] x86/pti: Check the return value of pti_user_pagetable_walk_pmd() Git-Commit-ID: 8c934e01a7ce685d98e970880f5941d79272c654 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 8c934e01a7ce685d98e970880f5941d79272c654 Gitweb: https://git.kernel.org/tip/8c934e01a7ce685d98e970880f5941d79272c654 Author: Jiang Biao AuthorDate: Fri, 20 Jul 2018 08:06:32 +0800 Committer: Thomas Gleixner CommitDate: Fri, 20 Jul 2018 07:07:39 +0200 x86/pti: Check the return value of pti_user_pagetable_walk_pmd() pti_user_pagetable_walk_pmd() can return NULL, so the return value should be checked to prevent a NULL pointer dereference. Add the check and a warning when the PMD allocation fails. Signed-off-by: Jiang Biao Signed-off-by: Thomas Gleixner Cc: dave.hansen@linux.intel.com Cc: luto@kernel.org Cc: hpa@zytor.com Cc: albcamus@gmail.com Cc: zhong.weidong@zte.com.cn Link: https://lkml.kernel.org/r/1532045192-49622-2-git-send-email-jiang.biao2@zte.com.cn --- arch/x86/mm/pti.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 001ee6b0619e..bcf35dac1920 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -205,7 +205,7 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address) BUILD_BUG_ON(p4d_large(*p4d) != 0); if (p4d_none(*p4d)) { unsigned long new_pud_page = __get_free_page(gfp); - if (!new_pud_page) + if (WARN_ON_ONCE(!new_pud_page)) return NULL; set_p4d(p4d, __p4d(_KERNPG_TABLE | __pa(new_pud_page))); @@ -219,7 +219,7 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address) } if (pud_none(*pud)) { unsigned long new_pmd_page = __get_free_page(gfp); - if (!new_pmd_page) + if (WARN_ON_ONCE(!new_pmd_page)) return NULL; set_pud(pud, __pud(_KERNPG_TABLE | __pa(new_pmd_page))); @@ -241,9 +241,13 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address) static __init pte_t *pti_user_pagetable_walk_pte(unsigned long address) { gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO); - pmd_t *pmd = pti_user_pagetable_walk_pmd(address); + pmd_t *pmd; pte_t *pte; + pmd = pti_user_pagetable_walk_pmd(address); + if (!pmd) + return NULL; + /* We can't do anything sensible if we hit a large mapping. */ if (pmd_large(*pmd)) { WARN_ON(1);