FAILED: Patch "driver core: enforce device_lock for driver_match_device()" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From dc23806a7c47ec5f1293aba407fb69519f976ee0 Mon Sep 17 00:00:00 2001
From: Gui-Dong Han <[email protected]>
Date: Wed, 14 Jan 2026 00:28:43 +0800
Subject: [PATCH] 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.

---
 drivers/base/base.h | 9 +++++++++
 drivers/base/bus.c  | 2 +-
 drivers/base/dd.c   | 2 +-
 3 files changed, 11 insertions(+), 2 deletions(-)

index 430cbefbc97ff..677320881af15 100644
@@ -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)

index 9eb7771706f01..331d750465e2f 100644
@@ -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 */

index bea8da5f8a3a9..ed3a076248169 100644
@@ -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;

2.51.0