Commit dc23806a authored Jan 14, 2026 by Gui-Dong Han Committed by Danilo Krummrich Jan 16, 2026

driver core: enforce device_lock for driver_match_device()

Currently, driver_match_device() is called from three sites. One site
(__device_attach_driver) holds device_lock(dev), but the other two
(bind_store and __driver_attach) do not. This inconsistency means that
bus match() callbacks are not guaranteed to be called with the lock
held.

Fix this by introducing driver_match_device_locked(), which guarantees
holding the device lock using a scoped guard. Replace the unlocked calls
in bind_store() and __driver_attach() with this new helper. Also add a
lock assertion to driver_match_device() to enforce this guarantee.

This consistency also fixes a known race condition. The driver_override
implementation relies on the device_lock, so the missing lock led to the
use-after-free (UAF) reported in Bugzilla for buses using this field.

Stress testing the two newly locked paths for 24 hours with
CONFIG_PROVE_LOCKING and CONFIG_LOCKDEP enabled showed no UAF recurrence
and no lockdep warnings.

Cc: stable@vger.kernel.org
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220789


Suggested-by: Qiu-ji Chen <chenqiuji666@gmail.com>
Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com>
Fixes: 49b420a1 ("driver core: check bus->match without holding device lock")
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Link: https://patch.msgid.link/20260113162843.12712-1-hanguidong02@gmail.com


Signed-off-by: Danilo Krummrich <dakr@kernel.org>

parent a995fe1a

drivers/base/base.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -182,9 +182,18 @@ void device_set_deferred_probe_reason(const struct device *dev, struct va_format
		static inline int driver_match_device(const struct device_driver *drv,
		struct device *dev)
		{
		device_lock_assert(dev);

		return drv->bus->match ? drv->bus->match(dev, drv) : 1;
		}

		static inline int driver_match_device_locked(const struct device_driver *drv,
		struct device *dev)
		{
		guard(device)(dev);
		return driver_match_device(drv, dev);
		}

		static inline void dev_sync_state(struct device *dev)
		{
		if (dev->bus->sync_state)

drivers/base/bus.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -263,7 +263,7 @@ static ssize_t bind_store(struct device_driver drv, const char buf,
		int err = -ENODEV;

		dev = bus_find_device_by_name(bus, NULL, buf);
		if (dev && driver_match_device(drv, dev)) {
		if (dev && driver_match_device_locked(drv, dev)) {
		err = device_driver_attach(drv, dev);
		if (!err) {
		/* success */

drivers/base/dd.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1180,7 +1180,7 @@ static int __driver_attach(struct device dev, void data)
		* is an error.
		*/

		ret = driver_match_device(drv, dev);
		ret = driver_match_device_locked(drv, dev);
		if (ret == 0) {
		/* no match */
		return 0;