Affected: Linux

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

platform/surface: acpi-notify: Check ACPI companion before use

Since every platform driver can be forced to match a device that doesn't match its list of device IDs because of device_match_driver_override(), platform drivers that rely on the existence of a device's ACPI companion object should verify its presence.

san_probe() dereferences the result of ACPI_COMPANION() when installing the GSBUS address space handler, so force-binding the driver to a device without an ACPI companion leads to a NULL pointer dereference. The dereference was introduced when the probe function was switched from ACPI_HANDLE() to ACPI_COMPANION().

Check the ACPI companion against NULL and return -ENODEV when it is missing, like commit e4865a56d013 ("ACPI: driver: Check ACPI_COMPANION() against NULL during probe") does for the core ACPI platform drivers.