[PATCH 00/12] treewide: Convert buses to use generic driver_override

Danilo Krummrich
2026-03-24T00:59:32Z

This is the follow-up of the driver_override generalization in [1], converting
the remaining 11 busses and removing the now-unused driver_set_override()
helper.

All of them (except AP, which has a different race condition) are prone to the
potential UAF described in [2], caused by accessing the driver_override field
from their corresponding match() callback.

In order to address this, the generalized driver_override field in struct device
is protected with a spinlock. The driver-core provides accessors, such as
device_match_driver_override(), device_has_driver_override() and
device_set_driver_override(), which all ensure proper locking internally.

Additionally, the driver-core provides a driver_override flag in struct
bus_type, which, once enabled, automatically registers generic sysfs callbacks,
allowing userspace to modify the driver_override field.

SPI and AP are a bit special; both print "\n" when driver_override is not set,
whereas all other buses (and thus the driver-core) produce "(null)\n" in this
case.

Hence, SPI and AP do not take advantage of the driver_override flag in struct
bus_type; AP additionally maintains a counter in its custom sysfs store().

Technically, we could support a custom fallback string when driver_override is
unset in struct bus_type, but only SPI would benefit from this, since AP has
additional custom logic in store() anyways.

(I'm not sure if there are userspace programs that strictly rely on this;
driverctl seems to check for both, but I rather not break some userspace tool
I'm not aware of. :)

This series is based on v7.0-rc5 with no additional dependencies, hence those
patches can be picked up by subsystems individually.

[1] https://lore.kernel.org/driver-core/20260303115720.48783-1-dakr@kernel.org/
[2] https://bugzilla.kernel.org/show_bug.cgi?id=220789
[3] https://gitlab.com/driverctl/driverctl/-/blob/0.121/driverctl?ref_type=tags#L99

Danilo Krummrich (12):
amba: use generic driver_override infrastructure
bus: fsl-mc: use generic driver_override infrastructure
cdx: use generic driver_override infrastructure
hv: vmbus: use generic driver_override infrastructure
PCI: use generic driver_override infrastructure
platform/wmi: use generic driver_override infrastructure
rpmsg: use generic driver_override infrastructure
vdpa: use generic driver_override infrastructure
s390/cio: use generic driver_override infrastructure
s390/ap: use generic driver_override infrastructure
spi: use generic driver_override infrastructure
driver core: remove driver_set_override()

drivers/amba/bus.c | 37 +++------------
drivers/base/driver.c | 75 ------------------------------
drivers/bus/fsl-mc/fsl-mc-bus.c | 43 +++--------------
drivers/cdx/cdx.c | 40 ++--------------
drivers/hv/vmbus_drv.c | 36 ++------------
drivers/pci/pci-driver.c | 11 +++--
drivers/pci/pci-sysfs.c | 28 -----------
drivers/pci/probe.c | 1 -
drivers/platform/wmi/core.c | 36 ++------------
drivers/rpmsg/qcom_glink_native.c | 2 -
drivers/rpmsg/rpmsg_core.c | 43 +++--------------
drivers/rpmsg/virtio_rpmsg_bus.c | 1 -
drivers/s390/cio/cio.h | 5 --
drivers/s390/cio/css.c | 34 ++------------
drivers/s390/crypto/ap_bus.c | 34 +++++++-------
drivers/s390/crypto/ap_bus.h | 1 -
drivers/s390/crypto/ap_queue.c | 24 +++-------
drivers/spi/spi.c | 19 +++-----
drivers/vdpa/vdpa.c | 48 ++-----------------
drivers/vfio/fsl-mc/vfio_fsl_mc.c | 4 +-
drivers/vfio/pci/vfio_pci_core.c | 5 +-
drivers/xen/xen-pciback/pci_stub.c | 6 ++-
include/linux/amba/bus.h | 5 --
include/linux/cdx/cdx_bus.h | 4 --
include/linux/device/driver.h | 2 -
include/linux/fsl/mc.h | 4 --
include/linux/hyperv.h | 5 --
include/linux/pci.h | 6 ---
include/linux/rpmsg.h | 4 --
include/linux/spi/spi.h | 5 --
include/linux/vdpa.h | 4 --
include/linux/wmi.h | 4 --
32 files changed, 88 insertions(+), 488 deletions(-)

base-commit: c369299895a591d96745d6492d4888259b004a9e
--
2.53.0