From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f199.google.com (mail-pg1-f199.google.com [209.85.215.199]) by kanga.kvack.org (Postfix) with ESMTP id B0E2C6B1C94 for ; Mon, 19 Nov 2018 16:54:21 -0500 (EST) Received: by mail-pg1-f199.google.com with SMTP id h9so16485975pgm.1 for ; Mon, 19 Nov 2018 13:54:21 -0800 (PST) Received: from mga11.intel.com (mga11.intel.com. [192.55.52.93]) by mx.google.com with ESMTPS id o12-v6si32492543plg.114.2018.11.19.13.54.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Nov 2018 13:54:20 -0800 (PST) From: 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> In-Reply-To: <20181119214809.6086-1-yu-cheng.yu@intel.com> References: <20181119214809.6086-1-yu-cheng.yu@intel.com> Sender: owner-linux-mm@kvack.org List-ID: 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 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