Re: [PATCH v2] pstore/ram: fix undefined usage of rounddown_pow_of_two(0)

[Kees Cook]

On Mon, Oct 22, 2012 at 2:19 AM, Florian Fainelli <ffainelli@xxxxxxxxxx> wrote:
> From: Maxime Bizon <mbizon@xxxxxxxxxx>
>
> record_size / console_size / ftrace_size can be 0 (this is how you
> disable the feature), but rounddown_pow_of_two(0) is undefined. As suggested
> by Kees Cook, use !is_power_of_2() as a condition to call rounddown_pow_of_two
> and avoid its undefined behavior on the value 0. This issue has been present
> since commit 1894a253 (ramoops: Move to fs/pstore/ram.c).
>
> CC: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Maxime Bizon <mbizon@xxxxxxxxxx>
> Signed-off-by: Florian Fainelli <ffainelli@xxxxxxxxxx>

Thanks for the fix!

Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>

-Kees

-- 
Kees Cook
Chrome OS Security
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