From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00C93C3F2D1 for ; Mon, 2 Mar 2020 13:53:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C94DC21739 for ; Mon, 2 Mar 2020 13:53:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="eV7BHwUe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727389AbgCBNx0 (ORCPT ); Mon, 2 Mar 2020 08:53:26 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:44758 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727273AbgCBNx0 (ORCPT ); Mon, 2 Mar 2020 08:53:26 -0500 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 022Dbu4C031928; Mon, 2 Mar 2020 13:53:07 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=h1eCHVy/pMUEf9B7gboazc7d0KQ49jfH5mCfHZatf7Q=; b=eV7BHwUe7VvQ7Kt+hr/ElSezfJ0lEMwJtDSugJlmszKeqpUnnyZ8g9swTlyZVhGCXprC Ofr7NK0d4GtKEqJW7VxZJqE1SjK/wi5uiFtCF4sgDWCvYtHj0SedY633JzjUInixTIai jrTUq4dNMYeJwELiatworTsn31COSuFInJOwaP1PHjk7Pbwir5DjQIsm7R86b3CLdq+/ /L9WEwO6jZjY9/2EhF7xE/MDeJEklbivyhGPRJ13k0MIFO+EYf/hPkb6WjX9CMa45kpI eYSuVFOYU0vMiV35noZnLMKMypRhdvIuGDqTOFjcbNs59umOh05i8to2GgOmmvYPyvun ZQ== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by aserp2120.oracle.com with ESMTP id 2yffwqftev-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 02 Mar 2020 13:53:07 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 022DqxgM100444; Mon, 2 Mar 2020 13:53:07 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3030.oracle.com with ESMTP id 2yg1gv50s2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 02 Mar 2020 13:53:07 +0000 Received: from abhmp0005.oracle.com (abhmp0005.oracle.com [141.146.116.11]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 022Dr35C022595; Mon, 2 Mar 2020 13:53:03 GMT Received: from kadam (/129.205.23.165) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 02 Mar 2020 05:53:03 -0800 Date: Mon, 2 Mar 2020 16:52:51 +0300 From: Dan Carpenter To: Alexander Potapenko Cc: Joe Perches , "open list:ANDROID DRIVERS" , Kees Cook , Jann Horn , Peter Zijlstra , Greg Kroah-Hartman , LKML , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Ingo Molnar , Dmitriy Vyukov , Todd Kjos Subject: Re: [PATCH v2 2/3] binder: do not initialize locals passed to copy_from_user() Message-ID: <20200302135251.GA24372@kadam> References: <20200302130430.201037-1-glider@google.com> <20200302130430.201037-2-glider@google.com> <0eaac427354844a4fcfb0d9843cf3024c6af21df.camel@perches.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9547 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 phishscore=0 suspectscore=0 malwarescore=0 mlxlogscore=999 mlxscore=0 spamscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003020102 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9547 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 spamscore=0 impostorscore=0 malwarescore=0 mlxlogscore=999 mlxscore=0 suspectscore=0 phishscore=0 clxscore=1011 bulkscore=0 adultscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003020101 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 02, 2020 at 02:25:51PM +0100, Alexander Potapenko wrote: > On Mon, Mar 2, 2020 at 2:11 PM Joe Perches wrote: > > > > On Mon, 2020-03-02 at 14:04 +0100, glider@google.com wrote: > > > Certain copy_from_user() invocations in binder.c are known to > > > unconditionally initialize locals before their first use, like e.g. in > > > the following case: > > [] > > > diff --git a/drivers/android/binder.c b/drivers/android/binder.c > > [] > > > @@ -3788,7 +3788,7 @@ static int binder_thread_write(struct binder_proc *proc, > > > > > > case BC_TRANSACTION_SG: > > > case BC_REPLY_SG: { > > > - struct binder_transaction_data_sg tr; > > > + struct binder_transaction_data_sg tr __no_initialize; > > > > > > if (copy_from_user(&tr, ptr, sizeof(tr))) > > > > I fail to see any value in marking tr with __no_initialize > > when it's immediately written to by copy_from_user. > > This is being done exactly because it's immediately written to by copy_to_user() > Clang is currently unable to figure out that copy_to_user() initializes memory. ^^ typo s/to/from/. It feels more useful to annotate copy_from_user(). That would be useful for Smatch as well. regards, dan carpenter