CVE-2026-64182: drivers/base/memory: fix memory block reference leak in poison accounting

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

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

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

drivers/base/memory: fix memory block reference leak in poison accounting

memblk_nr_poison_inc() and memblk_nr_poison_sub() look up a memory block
via find_memory_block_by_id(), which acquires a reference to the memory
block device.

Both helpers use the returned memory block without dropping that
reference, leaking the device reference on each successful lookup.  Drop
the reference after updating nr_hwpoison.

The Linux kernel CVE team has assigned CVE-2026-64182 to this issue.


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

	Issue introduced in 6.2 with commit 5033091de814ab4b5623faed2755f3064e19e2d2 and fixed in 6.6.142 with commit 686b4283f82cd630fafd7ca9b03dfc080b3ec8fa
	Issue introduced in 6.2 with commit 5033091de814ab4b5623faed2755f3064e19e2d2 and fixed in 6.12.92 with commit ce60d9452a0f2effa72fd20ea270c59ca691d455
	Issue introduced in 6.2 with commit 5033091de814ab4b5623faed2755f3064e19e2d2 and fixed in 6.18.34 with commit 24840b3139d7415144b81e4f9f4c44670d15bed9
	Issue introduced in 6.2 with commit 5033091de814ab4b5623faed2755f3064e19e2d2 and fixed in 7.0.11 with commit 8502e2c2d0633f99d94d22ae8dabc10caae1fc2a
	Issue introduced in 6.2 with commit 5033091de814ab4b5623faed2755f3064e19e2d2 and fixed in 7.1 with commit 03a2cc1756a0570f887d624cd6c535ea0cbd4951

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-2026-64182
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/base/memory.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/686b4283f82cd630fafd7ca9b03dfc080b3ec8fa
	https://git.kernel.org/stable/c/ce60d9452a0f2effa72fd20ea270c59ca691d455
	https://git.kernel.org/stable/c/24840b3139d7415144b81e4f9f4c44670d15bed9
	https://git.kernel.org/stable/c/8502e2c2d0633f99d94d22ae8dabc10caae1fc2a
	https://git.kernel.org/stable/c/03a2cc1756a0570f887d624cd6c535ea0cbd4951