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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 2F8D5C5DF60 for ; Thu, 7 Nov 2019 13:46:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E8A7B2077C for ; Thu, 7 Nov 2019 13:46:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=web.de header.i=@web.de header.b="puTI2Jbd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388920AbfKGNqQ (ORCPT ); Thu, 7 Nov 2019 08:46:16 -0500 Received: from mout.web.de ([212.227.17.12]:37367 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731058AbfKGNqQ (ORCPT ); Thu, 7 Nov 2019 08:46:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=web.de; s=dbaedf251592; t=1573134362; bh=RHwsmZfu4iRzxYZNEyr0qQy3SUcUgNwBxdLZdcmUjgc=; h=X-UI-Sender-Class:Subject:To:Cc:References:From:Date:In-Reply-To; b=puTI2JbdiOsRmIMIiinGR5mqOPHqBtjvUYQGcGIUTz8eQujnVksMCSOc6iavYpfcW c+RymsEqOr1K+HKCCoJkWyjBBk1lY/eH2j1uH7FKLoOu++pLEAoQuA197XT+S5s8YS jNJhxVxG3qtwxwl0Rv24hcCZT+Ma3YUyKXXSWWug= X-UI-Sender-Class: c548c8c5-30a9-4db5-a2e7-cb6cb037b8f9 Received: from [192.168.1.2] ([78.48.68.124]) by smtp.web.de (mrweb101 [213.165.67.124]) with ESMTPSA (Nemesis) id 0M5wrF-1hj1RD2UA5-00xvBX; Thu, 07 Nov 2019 14:46:02 +0100 Subject: Re: [PATCH v2] s390/pkey: Use memdup_user() rather than duplicating its implementation To: =?UTF-8?Q?Christian_Borntr=c3=a4ger?= , linux-s390@vger.kernel.org, Joe Perches , Harald Freudenberger , Heiko Carstens , Ingo Franzki , Vasily Gorbik Cc: LKML , kernel-janitors@vger.kernel.org, Kangjie Lu , Navid Emamdoost , Stephen McCamant References: <08422b7e-2071-ee52-049e-c3ac55bc67a9@web.de> <6137855bb4170c438c7436cbdb7dfd21639a8855.camel@perches.com> <833d7d5e-6ede-6bdd-a2cc-2da7f0b03908@de.ibm.com> From: Markus Elfring Autocrypt: addr=Markus.Elfring@web.de; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: <833d7d5e-6ede-6bdd-a2cc-2da7f0b03908@de.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:ih/E6MytGxAanl6pgyvwl9rZHT10wv4oanaEBNdSe8jsW/2Sbv/ ilid4DM8rLEjURQV/AZIIVgsxXxGrStpGW/Q47GHMmtK5OJPbXESpWSoA6SMBrzycPx1VSS Y7zsc3u4pfudlSU2p2ODfvxR2tkjM8AJkiNGkYd1brGlm/70D6RagbaxHhtyYgeJro0aLES /FzfE8ca3bk7oa4t5TeDw== X-UI-Out-Filterresults: notjunk:1;V03:K0:uLwzaTJ+JGI=:ydqvPCFhWfiRClaXqe47uq d/+dMes6X8dGWCysBu+/fkviNvTX9UQcxVVhF942Jnjd1nX5IFKiuoIlFiFaOIOhubRexTlhl s5IphzPym8ivRBtlQ4X0yXmk5l2woFXMzq1py0vQ3kvK8LS3X8VDaRe5J+xejI+g+AhoFHyOR jWGf7kW5ZlcaWqjsuI8ux2fccVePmFKec4OTkRay4YQb3MUnWoa0+kHhzDW+h6gbvbPJPVlFo TVbCzpTtzadu1jlfjJ7I7/gmtcR5qFdgYDX7BVhq7c8yOdBQ05/lz/J7LGuTYa/SKC46SHAkD QPsQzsF8qRvPDAQ0OOedzDZulScAkKOJdf5K97AX9j5fLjinMN9ASxGvY1M7lcHHB95V3bKtn qIrDNFnK9pJnm5GHBx1IcWHxq06E6p9Vu3cBsBMPhq2sChZJUmKJh7uSQ0GC225FvYBh36TAU F7fPkeifaQ/IjGNf7dostRAyD49rYuL+uibUYvdpIgi6dwpaZS4VZqhX8uRdKYQTMR7oTiTEK LcOSJDvOHldNwrq2Fb+GDdJHNjQUFf/yDzyfXqOcJO25B4pPXL28xC+Ez5mcYWhTnMi2so0Ab OxwOkHXa9vMxYoe/+Gddmlv5Hcygoy3C608VMnCa31xUbwn4tC12t4uO01CVlARsZ1EkxofJ6 qTY9XODFpvZDR6JxBOUcmGHOtwlfMpSHSF884IF2b11+i0h51cARsSz0ANSkn9DTnLqEuFlJA A/GPiEne20allxi8ocG3yS3LECCQo/GeQk0YgtIPtycDILUY6uH7WC7YD2CtSW0Nk3yHjAkWz UuesqQoje4MZwQsTxsLX63hYRKZD4b/rqIW7TGZGqAnZDyonmzgWJJjIel67hEBDIbsSz7y2v gtL6WMePmn38MB3hkzZDLquHhdHfkV8gJ2RjbMcTOiBxfuTlX0RBF52iwaJda/52g1WqcU+nG 5CUjl3n9Zxrlt/QNG98mOC93IkttgJ8+A7rH7Xg1E/DgqJq4r2NBcCy11a7/d0f1ZVhA3Fo3c mxAtLFw5qDiThuCca8pDPPhGy/h3cv7rI4uXBLab0KQcCu9vB10s4pT6kk8FksZIQJCLwltfj k2RvosviwDODttz7okBfVxDsH/QVAI8ROaEZJUWPHkiymleuuXy+3vaDw1tnUZnIDUJJqdQj1 8AJDBO2PT3nZZ7Ox8XHaGhuRA+DGy7fiDVOa90hstOIqn3tTwuyp2nu9C1U1eUfMprvPQnPKX ZBw3Ldby0SxXeU6kNIiZpO0wHdDG5QglnfsMH/BxgPesRlJOXvsRYFZtM7D8= Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> Reuse existing functionality from memdup_user() instead of keeping >> duplicate source code. >> >> Generated by: scripts/coccinelle/api/memdup_user.cocci >> >> Delete local variables which became unnecessary with this refactoring >> in two function implementations. >> >> Fixes: f2bbc96e7cfad3891b7bf9bd3e566b9b7ab4553d ("s390/pkey: add CCA AE= S cipher key support") > > With that patch description, the Fixes tag is wrong...but (see below) I wonder about such a conclusion together with your subsequent feedback. >> static void *_copy_apqns_from_user(void __user *uapqns, size_t nr_apqn= s) >> { > > This part below is not an equivalent replacement. The shown refactoring provides also different run time characteristics, doesn't it? > In fact you are fixing a bug here... Thanks for your acknowledgement. >> - void *kapqns =3D NULL; >> - size_t nbytes; >> - >> - if (uapqns && nr_apqns > 0) { >> - nbytes =3D nr_apqns * sizeof(struct pkey_apqn); >> - kapqns =3D kmalloc(nbytes, GFP_KERNEL); >> - if (!kapqns) >> - return ERR_PTR(-ENOMEM); >> - if (copy_from_user(kapqns, uapqns, nbytes)) > > .... here we would need to kfree kapqns, but we do not. So this is > a memory leak. Isnt it? This is another undesirable software weakness because of incomplete exception handling in the previous copy approach. > So indeed this is fixing something. But please rework your the patch > description accordingly. Can the final committer pick the opportunity up to extend the change description another bit? >> + if (!uapqns || nr_apqns <=3D 0) >> + return NULL; >> >> - return kapqns; >> + return memdup_user(uapqns, nr_apqns * sizeof(struct pkey_apqn)); >> } Would you like to add any tags for the presented software improvement? Regards, Markus