CVE-2026-64376: firmware_loader: fix device reference leak in firmware_upload_register()

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

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

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

firmware_loader: fix device reference leak in firmware_upload_register()

firmware_upload_register()
  -> fw_create_instance()
     -> device_initialize()

After fw_create_instance() succeeds, the lifetime of the embedded struct
device is expected to be managed through the device core reference
counting, since fw_create_instance() has already called
device_initialize().

In firmware_upload_register(), if alloc_lookup_fw_priv() fails after
fw_create_instance() succeeds, the code reaches free_fw_sysfs and frees
fw_sysfs directly instead of releasing the device reference with
put_device(). This may leave the reference count of the embedded struct
device unbalanced, resulting in a refcount leak.

The issue was identified by a static analysis tool I developed and
confirmed by manual review. Fix this by using put_device(fw_dev) in the
failure path and letting fw_dev_release() handle the final cleanup,
instead of freeing the instance directly from the error path.

The Linux kernel CVE team has assigned CVE-2026-64376 to this issue.


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

	Issue introduced in 5.19 with commit 97730bbb242cde22b7140acd202ffd88823886c9 and fixed in 6.1.178 with commit 517676ec7dfca064e08f94007a4abd21969de0a0
	Issue introduced in 5.19 with commit 97730bbb242cde22b7140acd202ffd88823886c9 and fixed in 6.6.145 with commit 46d403da376a8b7c1187193294953816e1a8d7fe
	Issue introduced in 5.19 with commit 97730bbb242cde22b7140acd202ffd88823886c9 and fixed in 6.12.96 with commit 2619b47a0c8114eef980a56ade7e3ef4b58eb384
	Issue introduced in 5.19 with commit 97730bbb242cde22b7140acd202ffd88823886c9 and fixed in 6.18.39 with commit 92f41769e5fd16bcd9ba97500d0517332e0a5b45
	Issue introduced in 5.19 with commit 97730bbb242cde22b7140acd202ffd88823886c9 and fixed in 7.1.4 with commit 15432f19562fdb9199cce6d9fc24db12c71ed574
	Issue introduced in 5.19 with commit 97730bbb242cde22b7140acd202ffd88823886c9 and fixed in 7.2-rc1 with commit 896df22ee57648b0c505bd76ddbc6b2341834696

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-2026-64376
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/firmware_loader/sysfs_upload.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/517676ec7dfca064e08f94007a4abd21969de0a0
	https://git.kernel.org/stable/c/46d403da376a8b7c1187193294953816e1a8d7fe
	https://git.kernel.org/stable/c/2619b47a0c8114eef980a56ade7e3ef4b58eb384
	https://git.kernel.org/stable/c/92f41769e5fd16bcd9ba97500d0517332e0a5b45
	https://git.kernel.org/stable/c/15432f19562fdb9199cce6d9fc24db12c71ed574
	https://git.kernel.org/stable/c/896df22ee57648b0c505bd76ddbc6b2341834696