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SubjectRe: [PATCH v2] pwm: improve args checking in pwm_apply_state()
On Fri, May 27, 2016 at 09:45:49AM -0700, Brian Norris wrote:
> It seems like in the process of refactoring pwm_config() to utilize the
> newly-introduced pwm_apply_state() API, some args/bounds checking was
> dropped.
>
> In particular, I noted that we are now allowing invalid period
> selections. e.g.:
>
> # echo 1 > /sys/class/pwm/pwmchip0/export
> # cat /sys/class/pwm/pwmchip0/pwm1/period
> 100
> # echo 101 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle
> [... driver may or may not reject the value, or trigger some logic bug ...]
>
> It's better to see:
>
> # echo 1 > /sys/class/pwm/pwmchip0/export
> # cat /sys/class/pwm/pwmchip0/pwm1/period
> 100
> # echo 101 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle
> -bash: echo: write error: Invalid argument
>
> This patch reintroduces some bounds checks in both pwm_config() (for its
> signed parameters; we don't want to convert negative values into large
> unsigned values) and in pwm_apply_state() (which fix the above described
> behavior, as well as other potential API misuses).
>
> Fixes: 5ec803edcb70 ("pwm: Add core infrastructure to allow atomic updates")
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> v2:
> * changed subject, as this covers more scope now
> * add Fixes tag, as this is a v4.7-rc regression
> * add more bounds/args checks in pwm_apply_state() and pwm_config()
>
> drivers/pwm/core.c | 3 ++-
> include/linux/pwm.h | 3 +++
> 2 files changed, 5 insertions(+), 1 deletion(-)

Applied, thanks.

Thierry
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