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pwm: Zero-initialize the pwm_state passed to driver's .get_state() 

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@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Uwe Kleine-König 2023-03-22 22:45:45 +01:00 committed by Thierry Reding
parent 8caa81eb95
commit 1271a7b98e
1 changed files with 10 additions and 2 deletions
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12
drivers/pwm/core.c
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@ -115,7 +115,14 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
} }
if (pwm->chip->ops->get_state) { 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); err = pwm->chip->ops->get_state(pwm->chip, pwm, &state);
trace_pwm_get(pwm, &state, err); trace_pwm_get(pwm, &state, err);
@ -448,7 +455,7 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
{ {
struct pwm_state *last = &pwm->last; struct pwm_state *last = &pwm->last;
struct pwm_chip *chip = pwm->chip; struct pwm_chip *chip = pwm->chip;
struct pwm_state s1, s2; struct pwm_state s1 = { 0 }, s2 = { 0 };
int err; int err;
if (!IS_ENABLED(CONFIG_PWM_DEBUG)) if (!IS_ENABLED(CONFIG_PWM_DEBUG))
@ -530,6 +537,7 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
return; return;
} }
*last = (struct pwm_state){ 0 };
err = chip->ops->get_state(chip, pwm, last); err = chip->ops->get_state(chip, pwm, last);
trace_pwm_get(pwm, last, err); trace_pwm_get(pwm, last, err);
if (err) if (err)