From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 24ADC7D8D5 for ; Mon, 19 Nov 2018 21:56:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731368AbeKTIUB (ORCPT ); Tue, 20 Nov 2018 03:20:01 -0500 Received: from mga09.intel.com ([134.134.136.24]:32094 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731430AbeKTIUA (ORCPT ); Tue, 20 Nov 2018 03:20:00 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Nov 2018 13:54:20 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,254,1539673200"; d="scan'208";a="93319857" Received: from yyu32-desk1.sc.intel.com ([143.183.136.147]) by orsmga008.jf.intel.com with ESMTP; 19 Nov 2018 13:54:19 -0800 From: Yu-cheng Yu To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue Cc: Yu-cheng Yu Subject: [RFC PATCH v6 09/26] mm/mmap: Prevent Shadow Stack VMA merges Date: Mon, 19 Nov 2018 13:47:52 -0800 Message-Id: <20181119214809.6086-10-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181119214809.6086-1-yu-cheng.yu@intel.com> References: <20181119214809.6086-1-yu-cheng.yu@intel.com> Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org To prevent function call/return spills into the next shadow stack area, do not merge shadow stack areas. Signed-off-by: Yu-cheng Yu --- mm/mmap.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/mmap.c b/mm/mmap.c index 6c04292e16a7..30836512ca79 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1147,6 +1147,12 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm, if (vm_flags & VM_SPECIAL) return NULL; + /* + * Do not merge shadow stack areas. + */ + if (vm_flags & VM_SHSTK) + return NULL; + if (prev) next = prev->vm_next; else -- 2.17.1