CVE-2022-48707

/// Technical description

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

cxl/region: Fix null pointer dereference for resetting decoder

Not all decoders have a reset callback.

The CXL specification allows a host bridge with a single root port to

have no explicit HDM decoders. Currently the region driver assumes there

are none. As such the CXL core creates a special pass through decoder

instance without a commit/reset callback.

Prior to this patch, the ->reset() callback was called unconditionally when

calling cxl_region_decode_reset. Thus a configuration with 1 Host Bridge,

1 Root Port, and one directly attached CXL type 3 device or multiple CXL

type 3 devices attached to downstream ports of a switch can cause a null

pointer dereference.

Before the fix, a kernel crash was observed when we destroy the region, and

a pass through decoder is reset.

The issue can be reproduced as below,

1) create a region with a CXL setup which includes a HB with a

single root port under which a m

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References