Subject: CVE-2024-39495: greybus: Fix use-after-free bug in gb_interface_release due to race condition.

From: Greg Kroah-Hartman <[email-masked]>

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

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

greybus: Fix use-after-free bug in gb_interface_release due to race condition.

In gb_interface_create, &intf->mode_switch_completion is bound with
gb_interface_mode_switch_work. Then it will be started by
gb_interface_request_mode_switch. Here is the relevant code.
if (!queue_work(system_long_wq, &intf->mode_switch_work)) {
	...
}

If we call gb_interface_release to make cleanup, there may be an
unfinished work. This function will call kfree to free the object
"intf". However, if gb_interface_mode_switch_work is scheduled to
run after kfree, it may cause use-after-free error as
gb_interface_mode_switch_work will use the object "intf".
The possible execution flow that may lead to the issue is as follows:

CPU0                            CPU1

                            |   gb_interface_create
                            |   gb_interface_request_mode_switch
gb_interface_release        |
kfree(intf) (free)          |
                            |   gb_interface_mode_switch_work
                            |   mutex_lock(&intf->mutex) (use)

Fix it by canceling the work before kfree.

The Linux kernel CVE team has assigned CVE-2024-39495 to this issue.

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

	Fixed in 5.4.279 with commit 74cd0a421896
	Fixed in 5.10.221 with commit 2b6bb0b4abfd
	Fixed in 5.15.162 with commit fb071f5c75d4
	Fixed in 6.1.95 with commit 9a733d69a4a5
	Fixed in 6.6.35 with commit 0b8fba38bdfb
	Fixed in 6.9.6 with commit 03ea2b129344
	Fixed in 6.10 with commit 5c9c5d7f26ac

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-2024-39495
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/greybus/interface.c

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/74cd0a421896b2e07eafe7da4275302bfecef201
	https://git.kernel.org/stable/c/2b6bb0b4abfd79b8698ee161bb73c0936a2aaf83
	https://git.kernel.org/stable/c/fb071f5c75d4b1c177824de74ee75f9dd34123b9
	https://git.kernel.org/stable/c/9a733d69a4a59c2d08620e6589d823c24be773dc
	https://git.kernel.org/stable/c/0b8fba38bdfb848fac52e71270b2aa3538c996ea
	https://git.kernel.org/stable/c/03ea2b129344152157418929f06726989efc0445
	https://git.kernel.org/stable/c/5c9c5d7f26acc2c669c1dcf57d1bb43ee99220ce