UBUNTU-CVE-2026-64376: Medium severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: firmwareloader: fix device reference leak in firmwareuploadregister() firmwareuploadregister() -> fwcreateinstance() -> deviceinitialize() After fwcreateinstance() succeeds, the lifetime of the embedded struct device is expected to be managed through the device core reference counting, since fwcreateinstance() has already called deviceinitialize(). In firmwareuploadregister(), if alloclookupfwpriv() fails after fwcreateinstance() succeeds, the code reaches freefwsysfs and frees fwsysfs directly instead of releasing the device reference with putdevice(). 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 putdevice(fwdev) in the failure path and letting fwdevrelease() handle the final cleanup, instead of freeing the instance directly from the error path.
Affected Software
Remediation
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-31.31.1 - Compensating control
In firmware_upload_register(), when alloc_lookup_fw_priv() fails after fw_create_instance() succeeds, call put_device(fw_dev) in the failure path and let fw_dev_release() perform the final cleanup instead of freeing fw_sysfs directly.
Event History
Frequently Asked Questions
What conditions are required to trigger the leak?
The failure path is reached only when firmware_upload_register() has successfully created a firmware-upload device instance, but alloc_lookup_fw_priv() subsequently fails. Exploitation requires local access and low privileges, as reflected in the supplied vector.
What is the practical impact?
The affected error path leaves the embedded device reference count unbalanced, causing a device reference leak. The supplied severity vector indicates an availability impact, with no confidentiality or integrity impact.
Which Ubuntu kernel packages are listed as affected?
The listed packages are ubuntu/linux-riscv, ubuntu/linux-realtime, ubuntu/linux-azure, ubuntu/linux-gcp, ubuntu/linux-azure-fde, ubuntu/linux-gke, ubuntu/linux-hwe-edge, ubuntu/linux-gkeop.
How is the issue fixed?
The corrected failure path uses put_device(fw_dev) rather than freeing the firmware sysfs instance directly. This lets fw_dev_release() perform the final cleanup through device-core reference counting.