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: 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>

diff --git a/drivers/base/base.h b/drivers/base/base.h
index 430cbefbc97ffa59bef12e07fd29a58d0c5844af..677320881af15bf04bd17672f14e0c037b4010b9 100644 (file)
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -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)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 9eb7771706f018ce51c7899acdd33aa567a74a73..331d750465e2fcc2a4b80df0a7ca91254dde36a9 100644 (file)
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -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 */

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index bea8da5f8a3a92dc37dd2bee5a1cd96e7cb593fe..ed3a0762481696ae958c9c21ee8abee2863b12a1 100644 (file)
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -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;