Re: [PATCH v3 04/11] drivers/base/devcoredump: convert devcd_count to counter_atomic32

Kees Cook
2020-10-09T18:02:35Z

On Fri, Oct 09, 2020 at 09:55:59AM -0600, Shuah Khan wrote:
> counter_atomic* is introduced to be used when a variable is used as
> a simple counter and doesn't guard object lifetimes. This clearly
> differentiates atomic_t usages that guard object lifetimes.
>
> counter_atomic* variables wrap around to INT_MIN when it overflows
> and should not be used to guard resource lifetimes, device usage and
> open counts that control state changes, and pm states.
>
> devcd_count is used to track dev_coredumpm device count and used in
> device name string. It doesn't guard object lifetimes, device usage
> counts, device open counts, and pm states. There is very little chance
> of this counter overflowing. Convert it to use counter_atomic32.
>
> This conversion doesn't change the overflow wrap around behavior.
>
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

--
Kees Cook