CVE-2026-89559: libnvdimm/labels: Prevent integer overflow in __nd_label_validate()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

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

libnvdimm/labels: Prevent integer overflow in __nd_label_validate()

The on-media namespace index field nslot is a u32 read from the DIMM
label storage area.  __nd_label_validate() bounds it against the config
area size, but sizeof_namespace_label() returns unsigned, so the product
nslot * label_size is evaluated in 32-bit and wraps modulo 2^32 before
the comparison.  A crafted nslot passes the bound and is then used as the
loop trip count in nd_label_data_init(), whose memset() walks off the end
of the config_size buffer: an out-of-bounds write.

The field is not trusted -- it comes from the medium, or from userspace
via ND_CMD_SET_CONFIG_DATA.  Evaluate the product in 64-bit so the bound
check is exact; conforming labels are unaffected.

The check was safe when introduced by commit 4a826c83db4e ("libnvdimm:
namespace indices: read and validate"): it multiplied by sizeof(struct
nd_namespace_label), a size_t, so on a 64-bit build the product did not
wrap.  Commit 564e871aa66f ("libnvdimm, label: add v1.2 nvdimm label
definitions") narrowed it to 32 bits when the label size became a runtime
value read via sizeof_namespace_label().

The Linux kernel CVE team has assigned CVE-2026-89559 to this issue.


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

	Issue introduced in 4.13 with commit 564e871aa66f548a947b23808d3140f326381f0c and fixed in 6.12.109 with commit e057efcc9c71d90099d9ee00bed0748d0e9fd586
	Issue introduced in 4.13 with commit 564e871aa66f548a947b23808d3140f326381f0c and fixed in 6.18.50 with commit 09e649117c54b7e1c004f22eaa19efbadd9ac856
	Issue introduced in 4.13 with commit 564e871aa66f548a947b23808d3140f326381f0c and fixed in 7.2.4 with commit 69a734359639fca16a0dd73ab17a34943e76c68b
	Issue introduced in 4.13 with commit 564e871aa66f548a947b23808d3140f326381f0c and fixed in 7.3-rc1 with commit 037770686126155eafc44501312989e2837b9659

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-2026-89559
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/nvdimm/label.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/e057efcc9c71d90099d9ee00bed0748d0e9fd586
	https://git.kernel.org/stable/c/09e649117c54b7e1c004f22eaa19efbadd9ac856
	https://git.kernel.org/stable/c/69a734359639fca16a0dd73ab17a34943e76c68b
	https://git.kernel.org/stable/c/037770686126155eafc44501312989e2837b9659