CVE-2026-64510: ACPI: NFIT: core: Fix acpi_nfit_init() error cleanup

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

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

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

ACPI: NFIT: core: Fix acpi_nfit_init() error cleanup

If acpi_nfit_init() fails after adding the acpi_desc object to the
acpi_descs list, that object is never removed from that list because
the acpi_nfit_shutdown() devm action is not added for the NFIT device
in that case.  Next, the acpi_nfit_init() failure causes
acpi_nfit_probe() to fail, the acpi_desc object is freed, and a
dangling pointer is left behind in the acpi_descs.  Any subsequent
ACPI Machine Check Exception will trigger nfit_handle_mce() which
iterates over acpi_descs and so a use-after-free will occur.

Moreover, if acpi_nfit_probe() returns 0 after installing a notify
handler for the NFIT device and without allocating the acpi_desc
object and setting the NFIT device's driver data pointer, the
acpi_desc object will be allocated by acpi_nfit_update_notify()
and acpi_nfit_init() will be called to initialize it.  Regardless
of whether or not acpi_nfit_init() fails in that case, the
acpi_nfit_shutdown() devm action is not added for the NFIT device
and acpi_desc is never removed from the acpi_descs list.  If the
acpi_desc object is freed subsequently on driver removal, any
subsequent ACPI MCE will lead to a use-after-free like in the
previous case.

To address the first issue mentioned above, make acpi_nfit_probe()
call acpi_nfit_shutdown() directly on acpi_nfit_init() failures and
to address the other one, add a remove callback to the driver and
make it call acpi_nfit_shutdown().  Also, since it is now possible to
pass NULL to acpi_nfit_shutdown() or the acpi_desc object passed to it
may not have been initialized, add checks against NULL for acpi_desc and
its nvdimm_bus field to that function and make acpi_nfit_unregister()
clear the latter after unregistering the NVDIMM bus.

The Linux kernel CVE team has assigned CVE-2026-64510 to this issue.


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

	Issue introduced in 4.6 with commit a61fe6f7902ecaa89d5e6c709490fc4324927134 and fixed in 5.10.261 with commit ee82078e776ae31266cc70fdf62ac17c3c6f100a
	Issue introduced in 4.6 with commit a61fe6f7902ecaa89d5e6c709490fc4324927134 and fixed in 5.15.212 with commit 6ff054cc02a763914773b026cacb429e5fbf64fa
	Issue introduced in 4.6 with commit a61fe6f7902ecaa89d5e6c709490fc4324927134 and fixed in 6.1.178 with commit b07d22a2d17ad6465c87bd5752bc70e4c16e0ee4
	Issue introduced in 4.6 with commit a61fe6f7902ecaa89d5e6c709490fc4324927134 and fixed in 6.6.145 with commit c127dbd832bd4b9aef8a749d9f491b74042f9b47
	Issue introduced in 4.6 with commit a61fe6f7902ecaa89d5e6c709490fc4324927134 and fixed in 6.12.97 with commit df7c92216a1583a76cb0cbf2f21cd68870609b05
	Issue introduced in 4.6 with commit a61fe6f7902ecaa89d5e6c709490fc4324927134 and fixed in 6.18.40 with commit 3b2628f7682aea8d9ce09ad4b9a3bd144b451eaa
	Issue introduced in 4.6 with commit a61fe6f7902ecaa89d5e6c709490fc4324927134 and fixed in 7.1.4 with commit 7d69235bdc581a4346e9bcd6a8bea37d3e1abd25
	Issue introduced in 4.6 with commit a61fe6f7902ecaa89d5e6c709490fc4324927134 and fixed in 7.2-rc1 with commit 38bf27511ef41bffebd157ec3eba41fc89ba59cd

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-2026-64510
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/acpi/nfit/core.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/ee82078e776ae31266cc70fdf62ac17c3c6f100a
	https://git.kernel.org/stable/c/6ff054cc02a763914773b026cacb429e5fbf64fa
	https://git.kernel.org/stable/c/b07d22a2d17ad6465c87bd5752bc70e4c16e0ee4
	https://git.kernel.org/stable/c/c127dbd832bd4b9aef8a749d9f491b74042f9b47
	https://git.kernel.org/stable/c/df7c92216a1583a76cb0cbf2f21cd68870609b05
	https://git.kernel.org/stable/c/3b2628f7682aea8d9ce09ad4b9a3bd144b451eaa
	https://git.kernel.org/stable/c/7d69235bdc581a4346e9bcd6a8bea37d3e1abd25
	https://git.kernel.org/stable/c/38bf27511ef41bffebd157ec3eba41fc89ba59cd