Received-SPF: pass (google.com: domain of linux-bluetooth-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <e1ea4926f105b456f6a86ce30a0380ee5f48fe6d.camel@sipsolutions.net>
Subject: Re: [PATCH 02/32] Introduce flexible array struct memcpy() helpers
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Keith Packard <keithp@keithp.com>,
        Kees Cook <keescook@chromium.org>
Cc:     "Gustavo A . R . Silva" <gustavoars@kernel.org>,
        Francis Laniel <laniel_francis@privacyrequired.com>,
        Daniel Axtens <dja@axtens.net>,
        Dan Williams <dan.j.williams@intel.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Tadeusz Struk <tadeusz.struk@linaro.org>,
        Alexei Starovoitov <ast@kernel.org>,
        alsa-devel@alsa-project.org, Al Viro <viro@zeniv.linux.org.uk>,
        Andrew Gabbasov <andrew_gabbasov@mentor.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Gross <agross@kernel.org>,
        Andy Lavr <andy.lavr@gmail.com>,
        Arend van Spriel <aspriel@gmail.com>,
        Baowen Zheng <baowen.zheng@corigine.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Bradley Grove <linuxdrivers@attotech.com>,
        brcm80211-dev-list.pdl@broadcom.com,
        Christian Brauner <brauner@kernel.org>,
        Christian =?ISO-8859-1?Q?G=F6ttsche?= <cgzones@googlemail.com>,
        Christian Lamparter <chunkeey@googlemail.com>,
        Chris Zankel <chris@zankel.net>,
        Cong Wang <cong.wang@bytedance.com>,
        David Gow <davidgow@google.com>,
        David Howells <dhowells@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
        devicetree@vger.kernel.org, Dexuan Cui <decui@microsoft.com>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        Eli Cohen <elic@nvidia.com>,
        Eric Dumazet <edumazet@google.com>,
        Eric Paris <eparis@parisplace.org>,
        Eugeniu Rosca <erosca@de.adit-jv.com>,
        Felipe Balbi <balbi@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Franky Lin <franky.lin@broadcom.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Gregory Greenman <gregory.greenman@intel.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Hante Meuleman <hante.meuleman@broadcom.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Hulk Robot <hulkci@huawei.com>,
        Jakub Kicinski <kuba@kernel.org>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        James Morris <jmorris@namei.org>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Jaroslav Kysela <perex@perex.cz>,
        Jason Gunthorpe <jgg@ziepe.ca>, Jens Axboe <axboe@kernel.dk>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        John Keeping <john@metanate.com>,
        Juergen Gross <jgross@suse.com>, Kalle Valo <kvalo@kernel.org>,
        keyrings@vger.kernel.org, kunit-dev@googlegroups.com,
        Kuniyuki Iwashima <kuniyu@amazon.co.jp>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Lee Jones <lee.jones@linaro.org>,
        Leon Romanovsky <leon@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        linux1394-devel@lists.sourceforge.net,
        linux-afs@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org,
        linux-arm-msm@vger.kernel.org, linux-bluetooth@vger.kernel.org,
        linux-hardening@vger.kernel.org, linux-hyperv@vger.kernel.org,
        linux-integrity@vger.kernel.org, linux-rdma@vger.kernel.org,
        linux-scsi@vger.kernel.org, linux-security-module@vger.kernel.org,
        linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org,
        linux-xtensa@linux-xtensa.org, llvm@lists.linux.dev,
        Loic Poulain <loic.poulain@linaro.org>,
        Louis Peens <louis.peens@corigine.com>,
        Luca Coelho <luciano.coelho@intel.com>,
        Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
        Marc Dionne <marc.dionne@auristor.com>,
        Marcel Holtmann <marcel@holtmann.org>,
        Mark Brown <broonie@kernel.org>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Max Filippov <jcmvbkbc@gmail.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        Muchun Song <songmuchun@bytedance.com>,
        Nathan Chancellor <nathan@kernel.org>, netdev@vger.kernel.org,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nuno =?ISO-8859-1?Q?S=E1?= <nuno.sa@analog.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Paul Moore <paul@paul-moore.com>,
        Rich Felker <dalias@aerifal.cx>,
        Rob Herring <robh+dt@kernel.org>,
        Russell King <linux@armlinux.org.uk>, selinux@vger.kernel.org,
        "Serge E. Hallyn" <serge@hallyn.com>,
        SHA-cyfmac-dev-list@infineon.com,
        Simon Horman <simon.horman@corigine.com>,
        Stefano Stabellini <sstabellini@kernel.org>,
        Stefan Richter <stefanr@s5r6.in-berlin.de>,
        Steffen Klassert <steffen.klassert@secunet.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Stephen Smalley <stephen.smalley.work@gmail.com>,
        Takashi Iwai <tiwai@suse.com>, Tom Rix <trix@redhat.com>,
        Udipto Goswami <quic_ugoswami@quicinc.com>,
        wcn36xx@lists.infradead.org, Wei Liu <wei.liu@kernel.org>,
        xen-devel@lists.xenproject.org,
        Xiu Jianfeng <xiujianfeng@huawei.com>,
        Yang Yingliang <yangyingliang@huawei.com>
Date:   Thu, 05 May 2022 22:12:53 +0200
In-Reply-To: <87pmkrpwrs.fsf@keithp.com>
References: <20220504014440.3697851-1-keescook@chromium.org>
         <20220504014440.3697851-3-keescook@chromium.org>
         <d3b73d80f66325fdfaf2d1f00ea97ab3db03146a.camel@sipsolutions.net>
         <202205040819.DEA70BD@keescook>
         <970a674df04271b5fd1971b495c6b11a996c20c2.camel@sipsolutions.net>
         <871qx8qabo.fsf@keithp.com> <202205051228.4D5B8CD624@keescook>
         <87pmkrpwrs.fsf@keithp.com>
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.42.4 (3.42.4-2.fc35) 
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Thu, 2022-05-05 at 13:08 -0700, Keith Packard wrote:


> I bet you've already considered the simpler form:
> 
>         struct something *instance = mem_to_flex_dup(byte_array, count, GFP_KERNEL);
>         if (IS_ERR(instance))
>             return PTR_ERR(instance);
> 

Sadly, this doesn't work in any way because mem_to_flex_dup() needs to
know at least the type, hence passing 'instance', which is simpler than
passing 'struct something'.

johannes