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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=no 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 74B51C352AA for ; Tue, 1 Oct 2019 19:00:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E0A420B7C for ; Tue, 1 Oct 2019 19:00:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="OrmAYS24" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726216AbfJATAL (ORCPT ); Tue, 1 Oct 2019 15:00:11 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:34414 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726151AbfJATAL (ORCPT ); Tue, 1 Oct 2019 15:00:11 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x91IxYHo170955; Tue, 1 Oct 2019 18:59:39 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-2019-08-05; bh=HUjdfKmYAiVYdwx/VKsfp7MDujfbx9y3CuLubHKJmJQ=; b=OrmAYS24/I71CUnEQyZTUymcuiWq3LRWiTUg8n1+xpq6/U3nn9Nj4GocSxAnQMyUDQ6D dVUMnqhzj9BpFlEoKrm7Q9JWe6SlBVCPOKeSeXXlrZ399R+A7mLrS/tWA2rCp+QjnNa2 TadeQG8HXt7813ftQ/1ijYxH9XH87l6KkA7kUYw7u35I/9i5+kxdeCTOOejmbUAxTQdI 3UniJbFJMOLfy2sw3uQ7mrnTqaBRg+opbB30KCJDJhFfYSkRQLLvYr1o2CJx5IJSjJ/g 6ch4FC0CY/h5kDj+KHdjqhPVqLVTeUD0bM6ibsT/uSWBfDpaxNltJk1JnyDoJEkajDYA +w== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2120.oracle.com with ESMTP id 2va05rr5k1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 01 Oct 2019 18:59:38 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x91IxSHw114015; Tue, 1 Oct 2019 18:59:38 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3030.oracle.com with ESMTP id 2vbsm2g30p-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 01 Oct 2019 18:59:37 +0000 Received: from abhmp0015.oracle.com (abhmp0015.oracle.com [141.146.116.21]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x91IxCMH006633; Tue, 1 Oct 2019 18:59:13 GMT Received: from kadam (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 01 Oct 2019 11:59:12 -0700 Date: Tue, 1 Oct 2019 21:58:55 +0300 From: Dan Carpenter To: Denis Efremov Cc: David Laight , "devel@driverdev.osuosl.org" , Jes Sorensen , Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , Hans de Goede , Bastien Nocera , Dmitry Vyukov , Larry Finger Subject: Re: [PATCH] staging: rtl8723bs: hal: Fix memcpy calls Message-ID: <20191001185730.GM29696@kadam> References: <20190930110141.29271-1-efremov@linux.com> <37b195b700394e95aa8329afc9f60431@AcuMS.aculab.com> <20191001135649.GH22609@kadam> <8d2e8196cae74ec4ae20e9c23e898207@AcuMS.aculab.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=9397 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910010152 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9397 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910010152 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Oct 01, 2019 at 06:13:21PM +0300, Denis Efremov wrote: > Just found an official documentation to this issue: > https://gcc.gnu.org/gcc-4.9/porting_to.html > "Null pointer checks may be optimized away more aggressively > ... > The pointers passed to memmove (and similar functions in ) must be non-null > even when nbytes==0, so GCC can use that information to remove the check after the > memmove call. Calling copy(p, NULL, 0) can therefore deference a null pointer and crash." > Correct. In glibc those functions are annotated as non-NULL. extern void *memcpy (void *__restrict __dest, const void *__restrict __src, size_t __n) __THROW __nonnull ((1, 2)); We aren't going to do that in the kernel. A second difference is that in the kernel we use -fno-delete-null-pointer-checks so it doesn't delete the NULL checks. regards, dan carpenter