From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: linux-pwm@vger.kernel.org
Cc: kernel@pengutronix.de
Subject: [PATCH 1/8] pwm: Ensure that pwm_chips are allocated using pwmchip_alloc()
Date: Sun, 17 Mar 2024 11:40:32 +0100 [thread overview]
Message-ID: <b2bf15914e7e064ed48832dbd9ba909584613a9b.1710670958.git.u.kleine-koenig@pengutronix.de> (raw)
In-Reply-To: <cover.1710670958.git.u.kleine-koenig@pengutronix.de>
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>
---
drivers/pwm/core.c | 10 ++++++++++
include/linux/pwm.h | 2 ++
2 files changed, 12 insertions(+)
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index d70f793ce4b3..fe83333c466a 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;
};
--
2.43.0
next prev parent reply other threads:[~2024-03-17 10:40 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-17 10:40 [PATCH 0/8] pwm: Add support for character devices Uwe Kleine-König
2024-03-17 10:40 ` Uwe Kleine-König [this message]
2024-03-17 10:40 ` [PATCH 2/8] pwm: Give some sysfs related variables and functions better names Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 3/8] pwm: Move contents of sysfs.c into core.c Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 4/8] pwm: Ensure a struct pwm has the same lifetime as its pwm_chip Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 5/8] pwm: Add a struct device to struct pwm_chip Uwe Kleine-König
2024-03-28 18:44 ` David Lechner
2024-03-29 10:19 ` Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 6/8] pwm: Make pwmchip_[sg]et_drvdata() a wrapper around dev_set_drvdata() Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 7/8] pwm: Add more locking Uwe Kleine-König
2024-03-18 7:28 ` Thorsten Scherer
[not found] ` <CGME20240404120932eucas1p1b3c1e07bf6f41f6330725148b0268b13@eucas1p1.samsung.com>
2024-04-04 12:09 ` Marek Szyprowski
2024-04-04 15:33 ` Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 8/8] pwm: Add support for pwmchip devices for faster and easier userspace access Uwe Kleine-König
2024-04-08 15:42 ` John Ernberg
2024-04-09 7:49 ` Uwe Kleine-König
2024-04-15 11:27 ` John Ernberg
2024-05-07 1:11 ` Kent Gibson
2024-05-07 6:12 ` Uwe Kleine-König
2024-04-13 9:22 ` [PATCH 0/8] pwm: Add support for character devices Uwe Kleine-König
2024-04-22 18:59 ` David Lechner
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