From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.7 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 9DF717D910 for ; Tue, 13 Aug 2019 21:05:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727239AbfHMVFn (ORCPT ); Tue, 13 Aug 2019 17:05:43 -0400 Received: from mga06.intel.com ([134.134.136.31]:16072 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726756AbfHMVCp (ORCPT ); Tue, 13 Aug 2019 17:02:45 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Aug 2019 14:02:45 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,382,1559545200"; d="scan'208";a="187901377" Received: from yyu32-desk1.sc.intel.com ([10.144.153.205]) by orsmga002.jf.intel.com with ESMTP; 13 Aug 2019 14:02:43 -0700 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 , Borislav Petkov , 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 , Dave Martin Cc: Yu-cheng Yu Subject: [PATCH v8 09/27] mm/mmap: Prevent Shadow Stack VMA merges Date: Tue, 13 Aug 2019 13:52:07 -0700 Message-Id: <20190813205225.12032-10-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190813205225.12032-1-yu-cheng.yu@intel.com> References: <20190813205225.12032-1-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 7e8c3e8ae75f..b1a921c0de63 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1149,6 +1149,12 @@ 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