CVE-2024-26761

/// Technical description

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

cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window

The Linux CXL subsystem is built on the assumption that HPA == SPA.

That is, the host physical address (HPA) the HDM decoder registers are

programmed with are system physical addresses (SPA).

During HDM decoder setup, the DVSEC CXL range registers (cxl-3.1,

8.1.3.8) are checked if the memory is enabled and the CXL range is in

a HPA window that is described in a CFMWS structure of the CXL host

bridge (cxl-3.1, 9.18.1.3).

Now, if the HPA is not an SPA, the CXL range does not match a CFMWS

window and the CXL memory range will be disabled then. The HDM decoder

stops working which causes system memory being disabled and further a

system hang during HDM decoder initialization, typically when a CXL

enabled kernel boots.

Prevent a system hang and do not disable the HDM decoder if the

decoder's CXL range is not found in a CFMWS window.

Note the

/// 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