From: Uwe Kleine-König u.kleine-koenig@pengutronix.de
commit 1271a7b98e7989ba6bb978e14403fc84efe16e13 upstream.
This is just to ensure that .usage_power is properly initialized and doesn't contain random stack data. The other members of struct pwm_state should get a value assigned in a successful call to .get_state(). So in the absence of bugs in driver implementations, this is only a safe-guard and no fix.
Reported-by: Munehisa Kamata kamatam@amazon.com Link: https://lore.kernel.org/r/20230310214004.2619480-1-u.kleine-koenig@pengutron... Signed-off-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de Signed-off-by: Thierry Reding thierry.reding@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pwm/core.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
--- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -115,7 +115,14 @@ static int pwm_device_request(struct pwm }
if (pwm->chip->ops->get_state) { - struct pwm_state state; + /* + * Zero-initialize state because most drivers are unaware of + * .usage_power. The other members of state are supposed to be + * set by lowlevel drivers. We still initialize the whole + * structure for simplicity even though this might paper over + * faulty implementations of .get_state(). + */ + struct pwm_state state = { 0, };
err = pwm->chip->ops->get_state(pwm->chip, pwm, &state); trace_pwm_get(pwm, &state, err); @@ -448,7 +455,7 @@ static void pwm_apply_state_debug(struct { struct pwm_state *last = &pwm->last; struct pwm_chip *chip = pwm->chip; - struct pwm_state s1, s2; + struct pwm_state s1 = { 0 }, s2 = { 0 }; int err;
if (!IS_ENABLED(CONFIG_PWM_DEBUG)) @@ -530,6 +537,7 @@ static void pwm_apply_state_debug(struct return; }
+ *last = (struct pwm_state){ 0 }; err = chip->ops->get_state(chip, pwm, last); trace_pwm_get(pwm, last, err); if (err)