linux-kernel - Re: [PATCH] clk_register_clkdev: handle callers needing format string

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: <CAAObsKAyKVM-Y4XZJZ-dPXnZZpQ4_ytovkshAXCWj6UFU7-XGw@mail.gmail.com>
Date:	Wed, 5 Aug 2015 15:09:07 +0200
From:	Tomeu Vizoso <tomeu@...euvizoso.net>
To:	Kees Cook <keescook@...omium.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-clk@...r.kernel.org
Subject: Re: [PATCH] clk_register_clkdev: handle callers needing format string

On 31 July 2015 at 21:03, Kees Cook <keescook@...omium.org> wrote:
> On Fri, Jul 31, 2015 at 2:13 AM, Tomeu Vizoso <tomeu@...euvizoso.net> wrote:
>> On 25 July 2015 at 01:20, Kees Cook <keescook@...omium.org> wrote:
>>> Many callers either use NULL or const strings for the third argument of
>>> clk_register_clkdev. For those that do not, this is a risk for format
>>> strings being accidentally processed (for example in device names). This
>>> adds the missing "%s" arguments to make sure format strings will not leak
>>> into the clkdev.
>>>
>>> Signed-off-by: Kees Cook <keescook@...omium.org>
>>> ---
>>
>> [...]
>>
>>> diff --git a/drivers/clk/tegra/clk.c b/drivers/clk/tegra/clk.c
>>> index 41cd87c67be6..97d9fb7e89ad 100644
>>> --- a/drivers/clk/tegra/clk.c
>>> +++ b/drivers/clk/tegra/clk.c
>>> @@ -296,7 +296,7 @@ void __init tegra_register_devclks(struct tegra_devclk *dev_clks, int num)
>>>
>>>         for (i = 0; i < num; i++, dev_clks++)
>>>                 clk_register_clkdev(clks[dev_clks->dt_id], dev_clks->con_id,
>>> -                               dev_clks->dev_id);
>>> +                               "%s", dev_clks->dev_id);
>>
>> This causes clocks to be registered with a dev_id string of "(null)",
>> which is causing lookups that used to succeed before to fail.
>
> Oh yuck. Yeah, clk_register_clkdev handles a NULL argument differently
> than other format-string style functions. Using
> clk_register_clkdev(..., dev_clks->dev_id ? "%s" : NULL,
> dev_clks->dev_id) seems really ugly to work around this, though.
> Perhaps the format string capability should be removed?

Yeah, that sounds good to me. At least, I don't see as that good of an
idea to save a few lines of code by making the API so prone to
mistakes.

Could this patch be removed from linux-next in the meantime?

Thanks,

Tomeu

> -Kees
>
> --
> Kees Cook
> Chrome OS Security
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/