linux-kernel - Re: [RFC/PATCH] of: Mark property::value as const

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <58AF6EE7.5050008@gmail.com>
Date:   Thu, 23 Feb 2017 15:23:19 -0800
From:   Frank Rowand <frowand.list@...il.com>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Stephen Boyd <stephen.boyd@...aro.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [RFC/PATCH] of: Mark property::value as const

On 02/23/17 14:09, Rob Herring wrote:
> On Thu, Feb 23, 2017 at 2:58 PM, Frank Rowand <frowand.list@...il.com> wrote:
>> On 02/23/17 11:54, Frank Rowand wrote:
>>> On 02/13/17 18:50, Stephen Boyd wrote:
>>>> The 'blob' we pass into populate_properties() is marked as const,
>>>> but we cast that const away when we assign the result of
>>>> fdt_getprop_by_offset() to pp->value. Let's mark value as const
>>>> instead, so that code can't mistakenly write to the value of the
>>>> property that we've so far advertised as const.
>>>>
>>>> Unfortunately, this exposes a problem with the fdt resolver code,
>>>> where we overwrite the value member of properties of phandles to
>>>> update them with their final value. Add a comment for now to
>>>> indicate where we're potentially writing over const data.
>>>
>>> The resolver should not be over writing anything in the FDT.  I'll
>>> look at what is going on there.
>>>
>>> The FDT we expose to user space should be the FDT we booted with,
>>> not something later modified.
>>
>> It seems that /sys/firmware/fdt is not documented.  I'll look into
>> fixing that.
> 
> That's because the "official" interface is /proc/device-tree/ which is
> now a symlink. IIRC, it is documented to use /proc/device-tree, not
> the sysfs path.
> 
> Rob
> .
> 


Documentation/ABI/testing/sysfs-firmware-ofw describes
/sys/firmware/devicetree/* but not /sys/firmware/fdt


It also describes the /proc/device-tree symlink to
/sys/firmware/devicetree/base as the official
stable ABI, as you mentioned.

So it is just fdt that I have not found the documentation
for.

-Frank