linux-kernel - Re: [PATCH] mtd: sa1100: avoid VLA in sa1100_setup

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Date:   Sun, 28 Oct 2018 19:13:26 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Boris Brezillon <boris.brezillon@...tlin.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>,
        linux-mtd <linux-mtd@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Olof Johansson <olof@...om.net>
Subject: Re: [PATCH] mtd: sa1100: avoid VLA in sa1100_setup_mtd

On Fri, Oct 12, 2018 at 2:22 AM, Boris Brezillon
<boris.brezillon@...tlin.com> wrote:
> On Fri, 12 Oct 2018 11:19:52 +0200
> Arnd Bergmann <arnd@...db.de> wrote:
>
>> On Fri, Oct 12, 2018 at 11:16 AM Boris Brezillon
>> <boris.brezillon@...tlin.com> wrote:
>> >
>> > Hi Arnd,
>> >
>> > On Wed, 10 Oct 2018 20:44:50 +0200
>> > Arnd Bergmann <arnd@...db.de> wrote:
>> >
>> > > Enabling -Wvla found another variable-length array with randconfig
>> > > testing:
>> > >
>> > > drivers/mtd/maps/sa1100-flash.c: In function 'sa1100_setup_mtd':
>> > > drivers/mtd/maps/sa1100-flash.c:224:10: error: ISO C90 forbids variable length array 'cdev' [-Werror=vla]
>> > >
>> > > As far as I can tell, there is an upper bound on the number of resources
>> > > that can be passed, based on the number of CS lines on the bus.
>> > > In practice, all boards we support have either one or two resources,
>> > > but using six to be on the safe side has no extra cost.
>> >
>> > Why not dynamically allocate cdev instead? That removes any kind of
>> > guessing on the max value, and it shouldn't hurt much since this code is
>> > in the probe path.
>>
>> Fine with me as well, If you prefer that one, please just add
>> Reported-by: Arnd Bergmann <arnd@...db.de>
>
> Oh, I thought I'd let you send a v2, but I can do it if you prefer.

Olof just pointed out to me that neither fix landed for this? What's
needed for this?

Thanks!

-- 
Kees Cook