diff options
| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2024-02-14 10:33:28 +0100 |
|---|---|---|
| committer | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2024-04-26 21:29:16 +0200 |
| commit | 05947224ff469bf17b3791fd009bc27ce5151997 (patch) | |
| tree | f0de00606652bfd6cc833e32ba5090198626f8de | |
| parent | 79dedfadb79e527ca4dc6f3727dace96e3333f82 (diff) | |
pwm: Ensure that pwm_chips are allocated using pwmchip_alloc()
Memory holding a struct device must not be freed before the reference
count drops to zero. So a struct pwm_chip must not live in memory
freed by a driver on unbind. All in-tree drivers were fixed accordingly,
but as out-of-tree drivers, that were not adapted, still compile fine,
catch these in pwmchip_add().
Link: https://lore.kernel.org/r/35f5b229c98f78b2f6ce2397259a4a936be477c0.1707900770.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
| -rw-r--r-- | drivers/pwm/core.c | 10 | ||||
| -rw-r--r-- | include/linux/pwm.h | 2 |
2 files changed, 12 insertions, 0 deletions
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 403525cc1783..d3f475eca97f 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -481,6 +481,7 @@ struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t chip->dev = parent; chip->npwm = npwm; + chip->uses_pwmchip_alloc = true; pwmchip_set_drvdata(chip, pwmchip_priv(chip)); @@ -561,6 +562,15 @@ int __pwmchip_add(struct pwm_chip *chip, struct module *owner) if (!chip || !pwmchip_parent(chip) || !chip->ops || !chip->npwm) return -EINVAL; + /* + * a struct pwm_chip must be allocated using (devm_)pwmchip_alloc, + * otherwise the embedded struct device might disappear too early + * resulting in memory corruption. + * Catch drivers that were not converted appropriately. + */ + if (!chip->uses_pwmchip_alloc) + return -EINVAL; + if (!pwm_ops_check(chip)) return -EINVAL; diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 4a6568dfdf3f..94a642a88817 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -272,6 +272,7 @@ struct pwm_ops { * @npwm: number of PWMs controlled by this chip * @of_xlate: request a PWM device given a device tree PWM specifier * @atomic: can the driver's ->apply() be called in atomic context + * @uses_pwmchip_alloc: signals if pwmchip_allow was used to allocate this chip * @driver_data: Private pointer for driver specific info * @pwms: array of PWM devices allocated by the framework */ @@ -287,6 +288,7 @@ struct pwm_chip { bool atomic; /* only used internally by the PWM framework */ + bool uses_pwmchip_alloc; void *driver_data; struct pwm_device *pwms; }; |