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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 26DBFC352AA for ; Tue, 1 Oct 2019 14:36:27 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 051B52054F for ; Tue, 1 Oct 2019 14:36:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 051B52054F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ACULAB.COM Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=driverdev-devel-bounces@linuxdriverproject.org Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 3A3D285308; Tue, 1 Oct 2019 14:36:26 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id FMke9zgzsHWB; Tue, 1 Oct 2019 14:36:24 +0000 (UTC) Received: from ash.osuosl.org (ash.osuosl.org [140.211.166.34]) by hemlock.osuosl.org (Postfix) with ESMTP id 9462E87634; Tue, 1 Oct 2019 14:36:24 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by ash.osuosl.org (Postfix) with ESMTP id 3DA0F1BF592 for ; Tue, 1 Oct 2019 14:36:23 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 284EC20462 for ; Tue, 1 Oct 2019 14:36:23 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id x4PR2Uk3529M for ; Tue, 1 Oct 2019 14:36:19 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [146.101.78.151]) by silver.osuosl.org (Postfix) with ESMTPS id E479820763 for ; Tue, 1 Oct 2019 14:36:14 +0000 (UTC) Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-217-OO_eyhEkOW2W7nALFS7WXw-1; Tue, 01 Oct 2019 15:36:10 +0100 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Tue, 1 Oct 2019 15:36:09 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Tue, 1 Oct 2019 15:36:09 +0100 From: David Laight To: 'Dan Carpenter' , Denis Efremov Subject: RE: [PATCH] staging: rtl8723bs: hal: Fix memcpy calls Thread-Topic: [PATCH] staging: rtl8723bs: hal: Fix memcpy calls Thread-Index: AQHVd36LU5ikVLKK6EuvH5wLNYQtMKdEMyLwgAGeKE+AAAh2kA== Date: Tue, 1 Oct 2019 14:36:09 +0000 Message-ID: <8d2e8196cae74ec4ae20e9c23e898207@AcuMS.aculab.com> References: <20190930110141.29271-1-efremov@linux.com> <37b195b700394e95aa8329afc9f60431@AcuMS.aculab.com> <20191001135649.GH22609@kadam> In-Reply-To: <20191001135649.GH22609@kadam> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-MC-Unique: OO_eyhEkOW2W7nALFS7WXw-1 X-Mimecast-Spam-Score: 0 X-BeenThere: driverdev-devel@linuxdriverproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Driver Project Developer List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" > From: Dan Carpenter > Sent: 01 October 2019 14:57 > Subject: Re: [PATCH] staging: rtl8723bs: hal: Fix memcpy calls ... > That's true for glibc memcpy() but not for the kernel memcpy(). In the > kernel there are lots of places which do a zero size memcpy(). And probably from NULL (or even garbage) pointers. After all a pointer to the end of an array (a + ARRAY_SIZE(a)) is valid but must not be dereferenced - so memcpy() can't dereference it's source address when the length is zero. > The glibc attitude is "the standard allows us to put knives here" so > let's put knives everywhere in the path. And the GCC attitude is let's > silently remove NULL checks instead of just printing a warning that the > NULL check isn't required... It could really make someone despondent. gcc is the one that add knives... This reminds me of me of a compiler that decided to optimise away checks for function addresses being NULL. At almost exactly the same time that ELF allowed for undefined weak symbols. Checking whether a function was actually present was non-trivial. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel