CVE-2024-26761 Information

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.

Reference

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