[PATCH 6.6 04/25] driver core: enforce device_lock for driver_match_device()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gui-Dong Han <hanguidong02@gmail.com>

commit dc23806a7c47ec5f1293aba407fb69519f976ee0 upstream.

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: 49b420a13ff9 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/base/base.h |    9 +++++++++
 drivers/base/bus.c  |    2 +-
 drivers/base/dd.c   |    2 +-
 3 files changed, 11 insertions(+), 2 deletions(-)

--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -165,9 +165,18 @@ void device_set_deferred_probe_reason(co
 static inline int driver_match_device(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(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)
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -263,7 +263,7 @@ static ssize_t bind_store(struct device_
 	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 */
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -1169,7 +1169,7 @@ static int __driver_attach(struct device
 	 * is an error.
 	 */
 
-	ret = driver_match_device(drv, dev);
+	ret = driver_match_device_locked(drv, dev);
 	if (ret == 0) {
 		/* no match */
 		return 0;