CVE-2026-89795 (GCVE-0-2026-89795)
Vulnerability from cvelistv5
Published
2026-09-16 10:30
Modified
2026-10-21 12:48
Severity ?
8.4 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: PCI: Allow per function PCI slots to fix slot reset on s390 On s390 systems, which use a machine level hypervisor, PCI devices are always accessed through a form of PCI pass-through which fundamentally operates on a per PCI function granularity. This is also reflected in the s390 PCI hotplug driver which creates hotplug slots for individual PCI functions. Its reset_slot() function, which is a wrapper for zpci_hot_reset_device(), thus also resets individual functions. Currently, the pci_create_slot() assigns the same pci_slot object to multifunction devices. This approach worked fine on s390 systems that only exposed virtual functions as individual PCI domains to the operating system. Since commit 44510d6fa0c0 ("s390/pci: Handling multifunctions") s390 supports exposing the topology of multifunction PCI devices by grouping them in a shared PCI domain. This creates a problem when resetting a function through the hotplug driver's slot_reset() interface. When attempting to reset a function through the hotplug driver, the shared slot assignment causes the wrong function to be reset instead of the intended one. It also leaks memory as we do create a pci_slot object for the function, but don't correctly free it in pci_slot_release(). Add a flag for struct pci_slot to allow per function PCI slots for functions managed through a hypervisor, which exposes individual PCI functions while retaining the topology. Since we can use all 8 bits for slot 'number' (for ARI devices), change slot 'number' u16 to account for special values PCI_SLOT_PLACEHOLDER and PCI_SLOT_ALL_DEVICES.
References
Impacted products
Vendor Product Version
Linux Linux Version: 44510d6fa0c00aa90b80075caa6b313b25927475
Version: 44510d6fa0c00aa90b80075caa6b313b25927475
Version: 44510d6fa0c00aa90b80075caa6b313b25927475
Version: 44510d6fa0c00aa90b80075caa6b313b25927475
Version: 44510d6fa0c00aa90b80075caa6b313b25927475
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/pci/pci.c",
            "drivers/pci/slot.c",
            "include/linux/pci.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            {
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/pci/pci.c",
            "drivers/pci/slot.c",
            "include/linux/pci.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.8"
            },
            {
              "lessThan": "5.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "5.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.112",
                  "versionStartIncluding": "5.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.52",
                  "versionStartIncluding": "5.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.5",
                  "versionStartIncluding": "5.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "5.8",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nPCI: Allow per function PCI slots to fix slot reset on s390\n\nOn s390 systems, which use a machine level hypervisor, PCI devices are\nalways accessed through a form of PCI pass-through which fundamentally\noperates on a per PCI function granularity. This is also reflected in the\ns390 PCI hotplug driver which creates hotplug slots for individual PCI\nfunctions. Its reset_slot() function, which is a wrapper for\nzpci_hot_reset_device(), thus also resets individual functions.\n\nCurrently, the pci_create_slot() assigns the same pci_slot object to\nmultifunction devices. This approach worked fine on s390 systems that only\nexposed virtual functions as individual PCI domains to the operating\nsystem.  Since commit 44510d6fa0c0 (\"s390/pci: Handling multifunctions\")\ns390 supports exposing the topology of multifunction PCI devices by\ngrouping them in a shared PCI domain. This creates a problem when resetting\na function through the hotplug driver\u0027s slot_reset() interface.\n\nWhen attempting to reset a function through the hotplug driver, the shared\nslot assignment causes the wrong function to be reset instead of the\nintended one. It also leaks memory as we do create a pci_slot object for\nthe function, but don\u0027t correctly free it in pci_slot_release().\n\nAdd a flag for struct pci_slot to allow per function PCI slots for\nfunctions managed through a hypervisor, which exposes individual PCI\nfunctions while retaining the topology. Since we can use all 8 bits for\nslot \u0027number\u0027 (for ARI devices), change slot \u0027number\u0027 u16 to account for\nspecial values PCI_SLOT_PLACEHOLDER and PCI_SLOT_ALL_DEVICES."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.4,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The flaw is reached from local PCI reset paths (sysfs device reset, VFIO_DEVICE_RESET, and vfio_pci_core_enable()) that call pci_try_reset_function() -\u003e pci_dev_reset_slot_function() -\u003e s390 reset_slot()/zpci_hot_reset_device(); there is no network or adjacent-radio path.\nAC:L - On s390 multifunction domains pci_create_slot() matches PCI_SLOT(devfn) against a full 8-bit slot number, so siblings/VFs are assigned the wrong pci_slot and a reset deterministically invokes the other function\u0027s hotplug reset_slot() with no race or attacker-uncontrollable layout.\nPR:L - vfio_pci_core_enable() and VFIO_DEVICE_RESET call pci_try_reset_function() with no capable() check on the IOMMU path; IBM Z/LinuxONE SR-IOV VF passthrough routinely grants that VFIO fd to an unprivileged qemu/tenant user rather than init-namespace root.\nUI:N - The attacker opens the assigned VFIO device or issues VFIO_DEVICE_RESET themselves; prior admin binding of the zPCI function to vfio-pci is deployment configuration, not victim interaction.\nS:C - Function reset uses the wrongly shared pci_slot and issues zpci_hot_reset_device() on a sibling/PF outside the caller\u0027s VFIO device set, bypassing VFIO\u0027s slot-wide membership check and crossing zPCI per-function isolation into host or other-tenant devices.\nC:N - This is a wrong-function hardware reset plus a pci_slot lifetime leak; it does not perform an out-of-bounds read, use-after-free, or other disclosure of kernel or other users\u0027 memory.\nI:H - zpci_hot_reset_device() disable/re-enable of the unintended function wipes that function\u0027s hardware state behind its owner\u0027s driver, destroying in-flight I/O and device configuration on a host PF or another tenant\u0027s NIC/storage function.\nA:H - Surprise reset of an in-use PF or sibling denies that device and all VFs behind it, and can oops the bound host driver which continues MMIO against a freshly reset zPCI function, causing host kernel availability loss."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:48:43.613Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/b4a80e9e639cf09ef5c66b7f262c9cb5ab37bdde"
        },
        {
          "url": "https://git.kernel.org/stable/c/0d1a7d67f45645106578d65181e4e492dd20ed79"
        },
        {
          "url": "https://git.kernel.org/stable/c/2050d900f9adbd6d6f38d30e182bcd9ad3108467"
        },
        {
          "url": "https://git.kernel.org/stable/c/ecdcceed4d377b02d4ea036b65f83f962c38ede7"
        },
        {
          "url": "https://git.kernel.org/stable/c/dcc5bec09e23bbc4f9de055a11fce9937244f2c8"
        }
      ],
      "title": "PCI: Allow per function PCI slots to fix slot reset on s390",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89795",
    "datePublished": "2026-09-16T10:30:26.529Z",
    "dateReserved": "2026-09-11T19:38:34.767Z",
    "dateUpdated": "2026-10-21T12:48:43.613Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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