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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 C6339ECDFB1 for ; Tue, 17 Jul 2018 07:25:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B7322086E for ; Tue, 17 Jul 2018 07:25:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8B7322086E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zte.com.cn 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 S1729642AbeGQH5A (ORCPT ); Tue, 17 Jul 2018 03:57:00 -0400 Received: from out1.zte.com.cn ([202.103.147.172]:52004 "EHLO mxct.zte.com.cn" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727052AbeGQH47 (ORCPT ); Tue, 17 Jul 2018 03:56:59 -0400 Received: from mse01.zte.com.cn (unknown [10.30.3.20]) by Forcepoint Email with ESMTPS id 5A7174573A6FD7092C97; Tue, 17 Jul 2018 15:25:37 +0800 (CST) Received: from notes_smtp.zte.com.cn ([10.30.1.239]) by mse01.zte.com.cn with ESMTP id w6H7P2xs019089; Tue, 17 Jul 2018 15:25:02 +0800 (GMT-8) (envelope-from jiang.biao2@zte.com.cn) Received: from localhost.localdomain ([10.75.10.200]) by szsmtp06.zte.com.cn (Lotus Domino Release 8.5.3FP6) with ESMTP id 2018071715250643-691814 ; Tue, 17 Jul 2018 15:25:06 +0800 From: Jiang Biao To: tglx@linutronix.de, mingo@redhat.com Cc: dave.hansen@linux.intel.com, luto@kernel.org, hpa@zytor.com, x86@kernel.org, albcamus@gmail.com, linux-kernel@vger.kernel.org, zhong.weidong@zte.com.cn, jiang.biao2@zte.com.cn Subject: [PATCH v2 1/2] x86/pti: check the return value of pti_user_pagetable_walk_p4d Date: Tue, 17 Jul 2018 15:23:21 +0800 Message-Id: <1531812202-37778-1-git-send-email-jiang.biao2@zte.com.cn> X-Mailer: git-send-email 1.8.3.1 X-MIMETrack: Itemize by SMTP Server on SZSMTP06/server/zte_ltd(Release 8.5.3FP6|November 21, 2013) at 2018-07-17 15:25:06, Serialize by Router on notes_smtp/zte_ltd(Release 9.0.1FP7|August 17, 2016) at 2018-07-17 15:24:58, Serialize complete at 2018-07-17 15:24:58 X-MAIL: mse01.zte.com.cn w6H7P2xs019089 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org pti_user_pagetable_walk_p4d() may return NULL, we should check the return value to avoid NULL pointer dereference. And add warning for fail allocation where NULL returned. Signed-off-by: Jiang Biao --- arch/x86/mm/pti.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 4d418e7..7c402e9 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -176,7 +176,7 @@ static p4d_t *pti_user_pagetable_walk_p4d(unsigned long address) if (pgd_none(*pgd)) { unsigned long new_p4d_page = __get_free_page(gfp); - if (!new_p4d_page) + if (WARN_ON(!new_p4d_page)) return NULL; set_pgd(pgd, __pgd(_KERNPG_TABLE | __pa(new_p4d_page))); @@ -195,8 +195,10 @@ static p4d_t *pti_user_pagetable_walk_p4d(unsigned long address) static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address) { gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO); - p4d_t *p4d = pti_user_pagetable_walk_p4d(address); pud_t *pud; + p4d_t *p4d = pti_user_pagetable_walk_p4d(address); + if (!p4d) + return NULL; BUILD_BUG_ON(p4d_large(*p4d) != 0); if (p4d_none(*p4d)) { @@ -354,6 +356,8 @@ static void __init pti_clone_p4d(unsigned long addr) pgd_t *kernel_pgd; user_p4d = pti_user_pagetable_walk_p4d(addr); + if (!user_p4d) + return; kernel_pgd = pgd_offset_k(addr); kernel_p4d = p4d_offset(kernel_pgd, addr); *user_p4d = *kernel_p4d; -- 2.7.4