From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f200.google.com (mail-pf1-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id C4EF26B0269 for ; Thu, 11 Oct 2018 11:20:47 -0400 (EDT) Received: by mail-pf1-f200.google.com with SMTP id v88-v6so8157414pfk.19 for ; Thu, 11 Oct 2018 08:20:47 -0700 (PDT) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTPS id d35-v6si29570683pla.116.2018.10.11.08.20.46 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 11 Oct 2018 08:20:46 -0700 (PDT) From: Yu-cheng Yu Subject: [PATCH v5 10/27] mm/mmap: Prevent Shadow Stack VMA merges Date: Thu, 11 Oct 2018 08:15:06 -0700 Message-Id: <20181011151523.27101-11-yu-cheng.yu@intel.com> In-Reply-To: <20181011151523.27101-1-yu-cheng.yu@intel.com> References: <20181011151523.27101-1-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, we 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 5f2b2b184c60..b85292014ec9 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1123,6 +1123,12 @@ 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