linux-kernel - Re: [PATCH] of: do not leak console options

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Date:   Wed, 6 Sep 2017 10:27:54 -0500
From:   Rob Herring <robh@...nel.org>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Grant Likely <grant.likely@...retlab.ca>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH] of: do not leak console options

On Wed, Sep 6, 2017 at 8:29 AM, Sergey Senozhatsky
<sergey.senozhatsky.work@...il.com> wrote:
> Hello,
>
> On (09/06/17 14:40), Petr Mladek wrote:
> [..]
>> > I wouldn't know :) let's find that out
>> >
>> > the patch used to pass `of_stdout_options' in v1 and v2
>> > https://patches.linaro.org/patch/41559/
>> >
>> > starting from v3 options are kstrdup-ed
>> > https://patchwork.kernel.org/patch/5398761/
>>
>> I was curious. The const char * was suggested by Grant Likely,
>> see https://lkml.kernel.org/r/CACxGe6tQ5rWzCUcS+_fFY+rjEyua2khApAoCVKpTuJAghU=N_w@mail.gmail.com
>> I guess that the reason was to make the of_find_node_by_path()
>> API clean.
>
> ok, thanks.
>
>> > > AFAICT, the only reason is options within the console/printk code is a
>> > > char * and not a const char *. I can't imagine that options need
>> > > modifications?
>> >
>> > as far as I can tell, ->match callback has side efects, sometimes.
>>
>> I hope that the match() callbacks does not have this kind of side
>> effects. I think that they initialize some stuff, assign some values.
>> But I hope that they do not modify given strings, like console
>> name or options. At leats I am unable to find any place.
>> But I am not 100% sure.
>
> yeah, seems like we can pass just char *options.
>
> const-ifying options (and brl options) on the printk side would probably
> be a better solution. need to check if we can do that, tho. that also
> would require touching printk API, struct console, struct console_cmdline,
> ->match callbacks of every console in the kernel, etc. not like a big deal,
> just potentially a bit of a noisy patch.
>
>
> Rob, Grant,
> will this dirty hack work for you? I can respin the patch.

Yes, as long as you intend to fix things later.

Rob