CVE-2024-26761 cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window

2024-04-0317:00:44

Linux

www.cve.org

linux kernel

vulnerability

resolved

cxl subsystem

hpa

spa

dvsec

cxl range

memory

cfmws

hdm decoder

hardware hang

AI Score

7.5

Confidence

High

EPSS

Percentile

15.5%

JSON

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.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/cxl/core/pci.c"
    ],
    "versions": [
      {
        "version": "34e37b4c432c",
        "lessThan": "031217128990",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "34e37b4c432c",
        "lessThan": "2cc1a530ab31",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "34e37b4c432c",
        "lessThan": "3a3181a71935",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "34e37b4c432c",
        "lessThan": "0cab68720598",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/cxl/core/pci.c"
    ],
    "versions": [
      {
        "version": "5.19",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.19",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.80",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.19",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7.7",
        "lessThanOrEqual": "6.7.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]