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 B347EC468C6 for ; Mon, 16 Jul 2018 04:22:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6EE252086E for ; Mon, 16 Jul 2018 04:22:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6EE252086E 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 S1728075AbeGPEro (ORCPT ); Mon, 16 Jul 2018 00:47:44 -0400 Received: from mxhk.zte.com.cn ([63.217.80.70]:7834 "EHLO mxhk.zte.com.cn" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727127AbeGPEri (ORCPT ); Mon, 16 Jul 2018 00:47:38 -0400 Received: from mse01.zte.com.cn (unknown [10.30.3.20]) by Forcepoint Email with ESMTPS id 69E81DDF87F75239BC30; Mon, 16 Jul 2018 12:06:34 +0800 (CST) Received: from notes_smtp.zte.com.cn ([10.30.1.239]) by mse01.zte.com.cn with ESMTP id w6G46Uws070871; Mon, 16 Jul 2018 12:06:30 +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 2018071612063159-486029 ; Mon, 16 Jul 2018 12:06:31 +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 1/5] x86/pti: check the return value of pti_user_pagetable_walk_p4d Date: Mon, 16 Jul 2018 12:03:36 +0800 Message-Id: <1531713820-24544-2-git-send-email-jiang.biao2@zte.com.cn> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1531713820-24544-1-git-send-email-jiang.biao2@zte.com.cn> References: <1531713820-24544-1-git-send-email-jiang.biao2@zte.com.cn> X-MIMETrack: Itemize by SMTP Server on SZSMTP06/server/zte_ltd(Release 8.5.3FP6|November 21, 2013) at 2018-07-16 12:06:31, Serialize by Router on notes_smtp/zte_ltd(Release 9.0.1FP7|August 17, 2016) at 2018-07-16 12:06:29, Serialize complete at 2018-07-16 12:06:29 X-MAIL: mse01.zte.com.cn w6G46Uws070871 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. Signed-off-by: Jiang Biao --- arch/x86/mm/pti.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 4d418e7..be9e5bc 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -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 (WARN_ON(!p4d)) + return NULL; BUILD_BUG_ON(p4d_large(*p4d) != 0); if (p4d_none(*p4d)) { @@ -354,6 +356,9 @@ static void __init pti_clone_p4d(unsigned long addr) pgd_t *kernel_pgd; user_p4d = pti_user_pagetable_walk_p4d(addr); + if (WARN_ON(!user_p4d)) + return; + kernel_pgd = pgd_offset_k(addr); kernel_p4d = p4d_offset(kernel_pgd, addr); *user_p4d = *kernel_p4d; -- 2.7.4