Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Yu-cheng Yu <yu-cheng.yu@intel.com>
To:     linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-mm@kvack.org, linux-arch@vger.kernel.org, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H.J. Lu" <hjl.tools@gmail.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Jonathan Corbet <corbet@lwn.net>,
        Oleg Nesterov <oleg@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
        Mike Kravetz <mike.kravetz@oracle.com>
Cc:     Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH 07/10] mm: Prevent mprotect from changing shadow stack
Date:   Thu,  7 Jun 2018 07:38:04 -0700
Message-Id: <20180607143807.3611-8-yu-cheng.yu@intel.com>
In-Reply-To: <20180607143807.3611-1-yu-cheng.yu@intel.com>
References: <20180607143807.3611-1-yu-cheng.yu@intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
 mm/mprotect.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 625608bc8962..128dcb880c12 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -446,6 +446,15 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
 	error = -ENOMEM;
 	if (!vma)
 		goto out;
+
+	/*
+	 * Do not allow changing shadow stack memory.
+	 */
+	if (vma->vm_flags & VM_SHSTK) {
+		error = -EINVAL;
+		goto out;
+	}
+
 	prev = vma->vm_prev;
 	if (unlikely(grows & PROT_GROWSDOWN)) {
 		if (vma->vm_start >= end)
-- 
2.15.1