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Message-ID: <1484056111.2133.16.camel@linux.intel.com>
Subject: Re: [PATCH v2 2/2] UBI: Make mtd parameter readable
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Richard Weinberger <richard.weinberger@gmail.com>
Cc: Artem Bityutskiy <dedekind1@gmail.com>, Boris Brezillon
 <boris.brezillon@free-electrons.com>, "linux-mtd@lists.infradead.org"
 <linux-mtd@lists.infradead.org>, Brian Norris <computersforpeace@gmail.com>
Date: Tue, 10 Jan 2017 15:48:31 +0200
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References: <20170110125643.10990-1-andriy.shevchenko@linux.intel.com>
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On Tue, 2017-01-10 at 14:33 +0100, Richard Weinberger wrote:
> Andy,
> 
> On Tue, Jan 10, 2017 at 1:56 PM, Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> > Fix permissions to allow read mtd parameter back (only for owner).
> > 
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
> Please CC all maintainers in future. Otherwise the chance is high that
> I'll miss a patch.

Noted.

> > -module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000);
> > +module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 0400);

> What is the use case?
> AFAIKT the permissions are 000

If it's not 0 in current case than you easily crash the kernel because
parser will be gone at that time. This is fixed by patch 1.

>  because a parser is involved and to
> "understand" the parameter,
> a reader needs the ubi_mtd_param_parse() function.

Are you implying that writer is a bot and reader is human being? 
The use case is obvious (any security reasons are implied?) -- allow
user to see what was written there in the first place.

Permissions 0000 are error prone.

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy