driver core: fix parent lock use-after-free on USB disconnect

USB interfaces should be probed with their parent USB device lock held
and the USB bus therefore sets the need_parent_lock bus flag so that
driver core takes the parent lock when needed.

Driver core is only guaranteed to hold a reference to the parent device
during initial probe however and nothing prevents the device and its
parent from being deregistered and the parent potentially freed, for
example, while iterating over devices in driver_attach() or
bus_rescan_devices_helper().

Since commit 524134d42231 ("USB: don't cancel queued resets when
unbinding drivers") USB interfaces hold a reference to their parent USB
device, but a parent hub may still go away while probing a USB device
(e.g. via the drivers_probe sysfs interface). This can lead to a
use-after-free when taking the parent device lock before checking the
device->p->dead flag of the device being probed.

As only USB interfaces actually need the parent lock, make the
need_parent_lock feature even more fine grained by making it a device
type rather than bus feature. By requiring that any users also make sure
that their devices hold a reference to their parents (like USB does),
driver core can lock a device and its parent without first checking if
the device has been deregistered.

Note that this will also increase parallelism when using asynchronous
probe as USB devices connected to the same hub can now be probed in
parallel.

Fixes: bf74ad5bc417 ("[PATCH] Hold the device's parent's lock during probe and remove")
Cc: stable@vger.kernel.org	# 2.6.16: 524134d42231: USB: don't cancel queued resets when unbinding drivers
Cc: stable@vger.kernel.org	# 2.6.16
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20261014133109.1392265-2-johan@kernel.org
[ Fix mention of bus vs. device type in __device_driver_{un}lock().
  - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

0 files changed, 0 insertions, 0 deletions