Message-ID: <2025061819-CVE-2022-50144-c72a@gregkh>
Date: Wed, 18 Jun 2025 13:03:29 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50144: soundwire: revisit driver bind/unbind and callbacks

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

soundwire: revisit driver bind/unbind and callbacks

In the SoundWire probe, we store a pointer from the driver ops into
the 'slave' structure. This can lead to kernel oopses when unbinding
codec drivers, e.g. with the following sequence to remove machine
driver and codec driver.

/sbin/modprobe -r snd_soc_sof_sdw
/sbin/modprobe -r snd_soc_rt711

The full details can be found in the BugLink below, for reference the
two following examples show different cases of driver ops/callbacks
being invoked after the driver .remove().

kernel: BUG: kernel NULL pointer dereference, address: 0000000000000150
kernel: Workqueue: events cdns_update_slave_status_work [soundwire_cadence]
kernel: RIP: 0010:mutex_lock+0x19/0x30
kernel: Call Trace:
kernel:  ? sdw_handle_slave_status+0x426/0xe00 [soundwire_bus 94ff184bf398570c3f8ff7efe9e32529f532e4ae]
kernel:  ? newidle_balance+0x26a/0x400
kernel:  ? cdns_update_slave_status_work+0x1e9/0x200 [soundwire_cadence 1bcf98eebe5ba9833cd433323769ac923c9c6f82]

kernel: BUG: unable to handle page fault for address: ffffffffc07654c8
kernel: Workqueue: pm pm_runtime_work
kernel: RIP: 0010:sdw_bus_prep_clk_stop+0x6f/0x160 [soundwire_bus]
kernel: Call Trace:
kernel:  <TASK>
kernel:  sdw_cdns_clock_stop+0xb5/0x1b0 [soundwire_cadence 1bcf98eebe5ba9833cd433323769ac923c9c6f82]
kernel:  intel_suspend_runtime+0x5f/0x120 [soundwire_intel aca858f7c87048d3152a4a41bb68abb9b663a1dd]
kernel:  ? dpm_sysfs_remove+0x60/0x60

This was not detected earlier in Intel tests since the tests first
remove the parent PCI device and shut down the bus. The sequence
above is a corner case which keeps the bus operational but without a
driver bound.

While trying to solve this kernel oopses, it became clear that the
existing SoundWire bus does not deal well with the unbind case.

Commit 528be501b7d4a ("soundwire: sdw_slave: add probe_complete structure and new fields")
added a 'probed' status variable and a 'probe_complete'
struct completion. This status is however not reset on remove and
likewise the 'probe complete' is not re-initialized, so the
bind/unbind/bind test cases would fail. The timeout used before the
'update_status' callback was also a bad idea in hindsight, there
should really be no timing assumption as to if and when a driver is
bound to a device.

An initial draft was based on device_lock() and device_unlock() was
tested. This proved too complicated, with deadlocks created during the
suspend-resume sequences, which also use the same device_lock/unlock()
as the bind/unbind sequences. On a CometLake device, a bad DSDT/BIOS
caused spurious resumes and the use of device_lock() caused hangs
during suspend. After multiple weeks or testing and painful
reverse-engineering of deadlocks on different devices, we looked for
alternatives that did not interfere with the device core.

A bus notifier was used successfully to keep track of DRIVER_BOUND and
DRIVER_UNBIND events. This solved the bind-unbind-bind case in tests,
but it can still be defeated with a theoretical corner case where the
memory is freed by a .remove while the callback is in use. The
notifier only helps make sure the driver callbacks are valid, but not
that the memory allocated in probe remains valid while the callbacks
are invoked.

This patch suggests the introduction of a new 'sdw_dev_lock' mutex
protecting probe/remove and all driver callbacks. Since this mutex is
'local' to SoundWire only, it does not interfere with existing locks
and does not create deadlocks. In addition, this patch removes the
'probe_complete' completion, instead we directly invoke the
'update_status' from the probe routine. That removes any sort of
timing dependency and a much better support for the device/driver
model, the driver could be bound before the bus started, or eons after
the bus started and the hardware would be properly initialized in all
cases.

BugLink: https://github.com/thesofproject/linux/issues/3531

The Linux kernel CVE team has assigned CVE-2022-50144 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 4.16 with commit 56d4fe31af77f684bed62fb8201e6327e6ddf4e6 and fixed in 5.15.61 with commit 250b46505175889c6b5958c3829f610f52199f5f
	Issue introduced in 4.16 with commit 56d4fe31af77f684bed62fb8201e6327e6ddf4e6 and fixed in 5.18.18 with commit 8fd6b03646b9a9e16d1ec19bd724cd6bd78e0ea5
	Issue introduced in 4.16 with commit 56d4fe31af77f684bed62fb8201e6327e6ddf4e6 and fixed in 5.19.2 with commit 432b30f08ca3303d2ebb22352cb04c4b6cfefe65
	Issue introduced in 4.16 with commit 56d4fe31af77f684bed62fb8201e6327e6ddf4e6 and fixed in 6.0 with commit bd29c00edd0a5dac8b6e7332bb470cd50f92e893

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-50144
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/soundwire/bus.c
	drivers/soundwire/bus_type.c
	drivers/soundwire/slave.c
	drivers/soundwire/stream.c
	include/linux/soundwire/sdw.h


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/250b46505175889c6b5958c3829f610f52199f5f
	https://git.kernel.org/stable/c/8fd6b03646b9a9e16d1ec19bd724cd6bd78e0ea5
	https://git.kernel.org/stable/c/432b30f08ca3303d2ebb22352cb04c4b6cfefe65
	https://git.kernel.org/stable/c/bd29c00edd0a5dac8b6e7332bb470cd50f92e893

Powered by blists - more mailing lists