Subject: CVE-2024-50059: ntb: ntb_hw_switchtec: Fix use after free vulnerability in switchtec_ntb_remove due to race condition

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

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

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

ntb: ntb_hw_switchtec: Fix use after free vulnerability in switchtec_ntb_remove due to race condition

In the switchtec_ntb_add function, it can call switchtec_ntb_init_sndev
function, then &sndev->check_link_status_work is bound with
check_link_status_work. switchtec_ntb_link_notification may be called
to start the work.

If we remove the module which will call switchtec_ntb_remove to make
cleanup, it will free sndev through kfree(sndev), while the work
mentioned above will be used. The sequence of operations that may lead
to a UAF bug is as follows:

CPU0                                 CPU1

                        | check_link_status_work
switchtec_ntb_remove    |
kfree(sndev);           |
                        | if (sndev->link_force_down)
                        | // use sndev

Fix it by ensuring that the work is canceled before proceeding with
the cleanup in switchtec_ntb_remove.

The Linux kernel CVE team has assigned CVE-2024-50059 to this issue.

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

	Fixed in 5.10.227 with commit b65018968782
	Fixed in 5.15.168 with commit 92728fceefda
	Fixed in 6.1.113 with commit 3ae45be84924
	Fixed in 6.6.57 with commit fa840ba4bd9f
	Fixed in 6.11.4 with commit 177925d9c871
	Fixed in 6.12-rc1 with commit e51aded92d42

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-2024-50059
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/ntb/hw/mscc/ntb_hw_switchtec.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/b650189687822b705711f0567a65a164a314d8df
	https://git.kernel.org/stable/c/92728fceefdaa2a0a3aae675f86193b006eeaa43
	https://git.kernel.org/stable/c/3ae45be8492460a35b5aebf6acac1f1d32708946
	https://git.kernel.org/stable/c/fa840ba4bd9f3bad7f104e5b32028ee73af8b3dd
	https://git.kernel.org/stable/c/177925d9c8715a897bb79eca62628862213ba956
	https://git.kernel.org/stable/c/e51aded92d42784313ba16c12f4f88cc4f973bbb