CVE-2026-53116
UnknownSummary
A vulnerability has been identified in the Linux kernel related to updating AP masks, which may lead to a use-after-free (UAF). The issue occurs when calling ap_bus_revise_bindings() without properly locking access to the driver_override field.
Risk Assessment
This vulnerability could lead to unexpected system behavior, posing a risk to the integrity and security of data within the organization. An attacker could potentially exploit this flaw to gain control over the system.
Recommendation
It is recommended to update the Linux kernel to the latest version that includes a fix for this vulnerability. Additionally, monitor systems for unauthorized changes in configuration.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: s390/ap: use generic driver_override infrastructure When the AP masks are updated via apmask_store() or aqmask_store(), ap_bus_revise_bindings() is called after ap_attr_mutex has been released. This calls __ap_revise_reserved(), which accesses the driver_override field without holding any lock, racing against a concurrent driver_override_store() that may free the old string, resulting in a potential UAF. Fix this by using the driver-core driver_override infrastructure, which protects all accesses with an internal spinlock. Note that unlike most other buses, the AP bus does not check driver_override in its match() callback; the override is checked in ap_device_probe() and __ap_revise_reserved() instead. Also note that we do not enable the driver_override feature of struct bus_type, as AP - in contrast to most other buses - passes "" to sysfs_emit() when the driver_override pointer is NULL. Thus, printing "\n" instead of "(null)\n". Additionally, AP has a custom counter that is modified in the corresponding custom driver_override_store().