Affected: Linux

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

platform/mellanox: mlxbf-pmc: Check ACPI_COMPANION() against NULL

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(), so platform drivers that rely on the existence of a device's ACPI companion object need to verify its presence.

mlxbf_pmc_probe() passes the result of ACPI_COMPANION() to acpi_device_hid(), which dereferences it, so force-binding the driver to a device without an ACPI companion leads to a NULL pointer dereference.

Accordingly, add a requisite ACPI_COMPANION() check against NULL to the mlxbf-pmc driver and return -ENODEV when the companion is missing.