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 change only fixes a hardware hang, but does not implement
HPA/SPA translation. Support for this can be added in a follow on
patch series.

Classification

CVE ID: CVE-2024-26761

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.05% (probability of being exploited)

EPSS Percentile: 17.83% (scored less or equal to compared to others)

EPSS Date: 2025-02-04 (when was this score calculated)

References

https://git.kernel.org/stable/c/031217128990d7f0ab8c46db1afb3cf1e075fd29
https://git.kernel.org/stable/c/2cc1a530ab31c65b52daf3cb5d0883c8b614ea69
https://git.kernel.org/stable/c/3a3181a71935774bda2398451256d7441426420b
https://git.kernel.org/stable/c/0cab687205986491302cd2e440ef1d253031c221

Timeline