CVE-2026-64477 (GCVE-0-2026-64477)
Vulnerability from cvelistv5
Published
2026-07-25 08:51
Modified
2026-08-17 04:56
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: x86,fs/resctrl: Prevent out-of-bounds access while offlining CPU when SNC enabled The architecture updates the cpu_mask in a domain's header to track which online CPUs are associated with the domain. When this mask becomes empty the architecture initiates offline of the domain that includes calling on resctrl fs to offline the domain. If it is a monitoring domain in which LLC occupancy is tracked resctrl fs forces the limbo handler to clear all busy RMID state associated with the domain. The limbo handler always reads the current event value associated with a busy RMID irrespective of it being checked as part of regular "is it still busy" check or whether it will be forced released anyway. When reading an RMID on a system with SNC enabled the "logical RMID" is converted to the "physical RMID" and this conversion requires the NUMA node ID of the resctrl monitoring domain that is in turn determined by querying the NUMA node ID of any CPU belonging to the monitoring domain. When the monitoring domain is going offline its cpu_mask is empty causing the NUMA node ID query via cpu_to_node() to be done with "nr_cpu_ids" as argument resulting in an out-of-bounds access. Refactor the limbo handler to skip reading the RMID when the RMID will just be forced to no longer be dirty in the domain anyway. Add a safety check to the architecture's RMID reader to protect against this scenario.
References
Impacted products
Vendor Product Version
Linux Linux Version: e13db55b5a0d447dea63cde772c1078405bbbf96
Version: e13db55b5a0d447dea63cde772c1078405bbbf96
Version: e13db55b5a0d447dea63cde772c1078405bbbf96
Version: e13db55b5a0d447dea63cde772c1078405bbbf96
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            "arch/x86/kernel/cpu/resctrl/monitor.c",
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86,fs/resctrl: Prevent out-of-bounds access while offlining CPU when SNC enabled\n\nThe architecture updates the cpu_mask in a domain\u0027s header to track which\nonline CPUs are associated with the domain. When this mask becomes empty\nthe architecture initiates offline of the domain that includes calling\non resctrl fs to offline the domain. If it is a monitoring domain in\nwhich LLC occupancy is tracked resctrl fs forces the limbo handler to\nclear all busy RMID state associated with the domain.\n\nThe limbo handler always reads the current event value associated with a\nbusy RMID irrespective of it being checked as part of regular \"is it still\nbusy\" check or whether it will be forced released anyway. When reading an\nRMID on a system with SNC enabled the \"logical RMID\" is converted to the\n\"physical RMID\" and this conversion requires the NUMA node ID of the\nresctrl monitoring domain that is in turn determined by querying the NUMA\nnode ID of any CPU belonging to the monitoring domain.\n\nWhen the monitoring domain is going offline its cpu_mask is empty causing\nthe NUMA node ID query via cpu_to_node() to be done with \"nr_cpu_ids\" as\nargument resulting in an out-of-bounds access.\n\nRefactor the limbo handler to skip reading the RMID when the RMID will\njust be forced to no longer be dirty in the domain anyway. Add a safety\ncheck to the architecture\u0027s RMID reader to protect against this scenario."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:56:23.686Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/ebc300b7ee0c669fa76a7a8858298ff32e296103"
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        },
        {
          "url": "https://git.kernel.org/stable/c/fc16126cc11d9f507130bf84ab137ee0938c900e"
        }
      ],
      "title": "x86,fs/resctrl: Prevent out-of-bounds access while offlining CPU when SNC enabled",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64477",
    "datePublished": "2026-07-25T08:51:39.558Z",
    "dateReserved": "2026-07-19T15:36:31.791Z",
    "dateUpdated": "2026-08-17T04:56:23.686Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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