CVE-2026-68152: amt: fix use-after-free in AMT delayed works

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

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

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

amt: fix use-after-free in AMT delayed works

When an AMT device is removed, pending delayed works can still access
the freed amt_dev structure, which may result in kernel crashes or
memory corruption.

amt_dev_stop() cancels req_wq and discovery_wq with
cancel_delayed_work_sync(), but these works can be scheduled again
from event_wq after the cancellation. This allows delayed works to
access the freed amt_dev structure after the netdev has been released.

The following is a simple race scenario:

CPU0                         CPU1

amt_dev_stop()
cancel_delayed_work_sync()
                             amt_event_work()
                             mod_delayed_work(req_wq)
free netdev
                             req_wq accesses freed amt_dev

Use disable_delayed_work_sync() in amt_dev_stop() to prevent req_wq and
discovery_wq from being queued again and wait for running work items
to complete.

The delayed works are disabled after initialization in
amt_newlink() and enabled only when the device is successfully opened.
This keeps the delayed work lifecycle synchronized with the lifetime
of the AMT device.

The Linux kernel CVE team has assigned CVE-2026-68152 to this issue.


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

	Issue introduced in 5.16 with commit cbc21dc1cfe949e37b2a54c71511579f1899e8d4 and fixed in 6.12.101 with commit a46bfa01e01df0f6f6dc4b0be18db002d6d2dbd2
	Issue introduced in 5.16 with commit cbc21dc1cfe949e37b2a54c71511579f1899e8d4 and fixed in 6.18.42 with commit 1a644db2cf59f164cdf3c75995bab5aadc097528
	Issue introduced in 5.16 with commit cbc21dc1cfe949e37b2a54c71511579f1899e8d4 and fixed in 7.1.6 with commit 006340cf06881b6ff49767d8b6f3c4f7b892670c
	Issue introduced in 5.16 with commit cbc21dc1cfe949e37b2a54c71511579f1899e8d4 and fixed in 7.2-rc5 with commit ea20c44935d6142daecfa9b39d635033a7553e1b

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-2026-68152
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/net/amt.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/a46bfa01e01df0f6f6dc4b0be18db002d6d2dbd2
	https://git.kernel.org/stable/c/1a644db2cf59f164cdf3c75995bab5aadc097528
	https://git.kernel.org/stable/c/006340cf06881b6ff49767d8b6f3c4f7b892670c
	https://git.kernel.org/stable/c/ea20c44935d6142daecfa9b39d635033a7553e1b