From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by kanga.kvack.org (Postfix) with ESMTP id 52A5C6B513C for ; Thu, 30 Aug 2018 07:41:33 -0400 (EDT) Received: by mail-wr1-f69.google.com with SMTP id u12-v6so5721236wrc.1 for ; Thu, 30 Aug 2018 04:41:33 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id r10-v6sor51084wmh.19.2018.08.30.04.41.31 for (Google Transport Security); Thu, 30 Aug 2018 04:41:31 -0700 (PDT) From: Andrey Konovalov Subject: [PATCH v6 07/11] fs, arm64: untag user address in copy_mount_options Date: Thu, 30 Aug 2018 13:41:12 +0200 Message-Id: <89806bc1c1f85fa97c62887075cc2d46b8bdeee2.1535629099.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Catalin Marinas , Will Deacon , Mark Rutland , Robin Murphy , Al Viro , Andrey Konovalov , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Shuah Khan , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Chintan Pandya In copy_mount_options a user address is being subtracted from TASK_SIZE. If the address is lower than TASK_SIZE, the size is calculated to not allow the exact_copy_from_user() call to cross TASK_SIZE boundary. However if the address is tagged, then the size will be calculated incorrectly. Untag the address before subtracting. Signed-off-by: Andrey Konovalov --- fs/namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/namespace.c b/fs/namespace.c index 99186556f8d3..51f763fb9430 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2672,7 +2672,7 @@ void *copy_mount_options(const void __user * data) * the remainder of the page. */ /* copy_from_user cannot cross TASK_SIZE ! */ - size = TASK_SIZE - (unsigned long)data; + size = TASK_SIZE - (unsigned long)untagged_addr(data); if (size > PAGE_SIZE) size = PAGE_SIZE; -- 2.19.0.rc0.228.g281dcd1b4d0-goog