linux-kernel - Re: [PATCH v2 1/3] nvmem: core: make default user binary file root-access only

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Message-ID: <56152250.2000200@linaro.org>
Date:	Wed, 07 Oct 2015 14:46:56 +0100
From:	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	gregkh@...uxfoundation.org, stefan.wahren@...e.com, andrew@...n.ch,
	s.hauer@...gutronix.de, pantelis.antoniou@...sulko.com,
	linux-kernel@...r.kernel.org, maitysanchayan@...il.com,
	p.zabel@...gutronix.de, maxime.ripard@...e-electrons.com,
	linux-arm-kernel@...ts.infradead.org, wxt@...k-chips.com
Subject: Re: [PATCH v2 1/3] nvmem: core: make default user binary file root-access
 only



On 07/10/15 12:33, Russell King - ARM Linux wrote:
> On Wed, Oct 07, 2015 at 12:00:47PM +0100, Srinivas Kandagatla wrote:
>> As required by many providers like at24/at25/mxs-ocotp/qfprom and may be
>> other providers would want to allow root-only to read the nvmem content.
>> So making the defaults to be root-only access would address the request
>> and also provide flexibility to providers to specify there own permissions
>> on top of the root-only using the perm flag in nvmem_config.
>> Making this dynamic did cut down lot of static binary attributes in the
>> code.
>
> Check what the lifetime of a struct bin_attribute is before you embed it
> into any other structure.  Sorry, but I think you're going to have to

Lifetime of the "static struct bin_attribute bin_attr_template" is 
static and a memcpy of which is made into nvmem->bin whose lifetime is 
till the nvmem_release() which happens at device_release(), so there 
should be no issue in using a copy of bin_attribute.

However there are other issues as Greg pointed, so am dropping this 
series altogether.

--srini
> read up on the driver model, sysfs, and kernfs implementations to find
> out - I don't know the answer to this without doing the same.
>
> However, this is basic checking that anyone should do when embedding
> a structure within another.
>
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