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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 12716C47094 for ; Thu, 10 Jun 2021 12:28:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E8F4F61285 for ; Thu, 10 Jun 2021 12:28:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230466AbhFJMaH (ORCPT ); Thu, 10 Jun 2021 08:30:07 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:9067 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230435AbhFJM3R (ORCPT ); Thu, 10 Jun 2021 08:29:17 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4G137Z0QDZzYWFY; Thu, 10 Jun 2021 20:24:26 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 10 Jun 2021 20:27:16 +0800 Received: from localhost.localdomain.localdomain (10.175.113.25) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 10 Jun 2021 20:27:11 +0800 From: Kefeng Wang To: Russell King , CC: Catalin Marinas , , Andrew Morton , Jungseung Lee , Will Deacon , Kefeng Wang Subject: [PATCH v3 6/6] ARM: mm: Fix PXN process with LPAE feature Date: Thu, 10 Jun 2021 20:35:56 +0800 Message-ID: <20210610123556.171328-7-wangkefeng.wang@huawei.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210610123556.171328-1-wangkefeng.wang@huawei.com> References: <20210610123556.171328-1-wangkefeng.wang@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.113.25] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When user code execution with privilege mode, it will lead to infinite loop in the page fault handler if ARM_LPAE enabled, The issue could be reproduced with "echo EXEC_USERSPACE > /sys/kernel/debug/provoke-crash/DIRECT" As Permission fault shows in ARM spec, IFSR format when using the Short-descriptor translation table format Permission fault: 01101 First level 01111 Second level IFSR format when using the Long-descriptor translation table format Permission fault: 0011LL LL bits indicate levelb. Add is_permission_fault() function to check permission fault and die if permission fault occurred under instruction fault in do_page_fault(). Fixes: 1d4d37159d01 ("ARM: 8235/1: Support for the PXN CPU feature on ARMv7") Signed-off-by: Kefeng Wang --- arch/arm/mm/fault.c | 20 +++++++++++++++++++- arch/arm/mm/fault.h | 4 ++++ 2 files changed, 23 insertions(+), 1 deletion(-) diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index 82bcfe57de20..bc8779d54a64 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -194,6 +194,19 @@ void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs) #define VM_FAULT_BADMAP 0x010000 #define VM_FAULT_BADACCESS 0x020000 +static inline bool is_permission_fault(unsigned int fsr) +{ + int fs = fsr_fs(fsr); +#ifdef CONFIG_ARM_LPAE + if ((fs & FS_PERM_NOLL_MASK) == FS_PERM_NOLL) + return true; +#else + if (fs == FS_L1_PERM || fs == FS_L2_PERM) + return true; +#endif + return false; +} + static vm_fault_t __kprobes __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int flags, unsigned long vma_flags, struct pt_regs *regs) @@ -253,9 +266,14 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) vm_flags = VM_WRITE; } - if (fsr & FSR_LNX_PF) + if (fsr & FSR_LNX_PF) { vm_flags = VM_EXEC; + if (is_permission_fault(fsr) && !user_mode(regs)) + die_kernel_fault("execution of memory", + mm, addr, fsr, regs); + } + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); /* diff --git a/arch/arm/mm/fault.h b/arch/arm/mm/fault.h index 9ecc2097a87a..83b5ab32d7a4 100644 --- a/arch/arm/mm/fault.h +++ b/arch/arm/mm/fault.h @@ -14,6 +14,8 @@ #ifdef CONFIG_ARM_LPAE #define FSR_FS_AEA 17 +#define FS_PERM_NOLL 0xC +#define FS_PERM_NOLL_MASK 0x3C static inline int fsr_fs(unsigned int fsr) { @@ -21,6 +23,8 @@ static inline int fsr_fs(unsigned int fsr) } #else #define FSR_FS_AEA 22 +#define FS_L1_PERM 0xD +#define FS_L2_PERM 0xF static inline int fsr_fs(unsigned int fsr) { -- 2.26.2