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[72.110.105.88]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a3e3c3ae21sm201715415ad.7.2026.01.13.08.28.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Jan 2026 08:29:02 -0800 (PST) From: Gui-Dong Han To: gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org Cc: linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, Gui-Dong Han , Qiu-ji Chen Subject: [PATCH v5] driver core: enforce device_lock for driver_match_device() Date: Wed, 14 Jan 2026 00:28:43 +0800 Message-ID: <20260113162843.12712-1-hanguidong02@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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. Closes: https://bugzilla.kernel.org/show_bug.cgi?id=3D220789 Suggested-by: Qiu-ji Chen Signed-off-by: Gui-Dong Han Reported-by: Gui-Dong Han Reviewed-by: Danilo Krummrich Reviewed-by: Greg Kroah-Hartman Reviewed-by: Rafael J. Wysocki (Intel) Tested-by: Wang Jiayue --- v5: * Introduce driver_match_device_locked() helper using guard(device) to handle locking, as suggested by Rafael J. Wysocki. v4: * Remove the misleading comment above device_lock_assert(), and update subject and commit message to focus on enforcing consistent locking, as discussed with Danilo Krummrich. v3: * Remove redundant locking comments at call sites and add a blank line after the lock assertion in driver_match_device(), as suggested by Greg KH. v2: * Add device_lock_assert() in driver_match_device() to enforce locking requirement, as suggested by Greg KH. v1: * The Bugzilla entry contains full KASAN reports and two PoCs that reliably reproduce the UAF on both unlocked paths using a standard QEMU setup (default e1000 device at 0000:00:03.0). --- drivers/base/base.h | 9 +++++++++ drivers/base/bus.c | 2 +- drivers/base/dd.c | 2 +- 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/base/base.h b/drivers/base/base.h index 430cbefbc97f..677320881af1 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -182,9 +182,18 @@ void device_set_deferred_probe_reason(const struct dev= ice *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; } =20 +static inline int driver_match_device_locked(const struct device_driver *d= rv, + 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 9eb7771706f0..331d750465e2 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -263,7 +263,7 @@ static ssize_t bind_store(struct device_driver *drv, co= nst char *buf, int err =3D -ENODEV; =20 dev =3D bus_find_device_by_name(bus, NULL, buf); - if (dev && driver_match_device(drv, dev)) { + if (dev && driver_match_device_locked(drv, dev)) { err =3D device_driver_attach(drv, dev); if (!err) { /* success */ diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 349f31bedfa1..98feb4c77160 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -1178,7 +1178,7 @@ static int __driver_attach(struct device *dev, void *= data) * is an error. */ =20 - ret =3D driver_match_device(drv, dev); + ret =3D driver_match_device_locked(drv, dev); if (ret =3D=3D 0) { /* no match */ return 0; --=20 2.43.0