CVE-2026-80548 (GCVE-0-2026-80548)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:37 – Updated: 2026-08-27 12:40
VLAI
Title
s390/vfio_ccw: Selectively expand io_mutex
Summary
In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Selectively expand io_mutex The io_mutex was defined to serialize the io_regions, but then has also sort of been associated with the I/O themselves because of the close relationship they share. With the handful of races that are possible, the choices are either to: A) expand the scope of io_mutex to close these remaining windows, or B) reduce the scope of io_mutex to just io_region, and introduce a new lock mechanism for the remaining I/O resources This patch implements A, since B brings with it a lot more interactions that would need to be tracked and kept in a correct hierarchy. It also takes advantage of the workqueue element for cp_free() that now gets called out of fsm_notoper(), which could be invoked out of an interrupt context and thus cannot acquire a mutex itself.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 4f76617378ee97c557b526cb58d3c61eb0a9c963 , < dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0 (git)
Affected: 4f76617378ee97c557b526cb58d3c61eb0a9c963 , < 56d7488533ceac4e986e96e15c9e487a2245bc01 (git)
Affected: 4f76617378ee97c557b526cb58d3c61eb0a9c963 , < f72a51810d49411bd8cad0c2df8592320a2fe5cc (git)
Affected: 4f76617378ee97c557b526cb58d3c61eb0a9c963 , < 2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd (git)
Affected: 4f76617378ee97c557b526cb58d3c61eb0a9c963 , < b6aecea4b2b246f9fbd98a5712daa1193a60818e (git)
Affected: 4f76617378ee97c557b526cb58d3c61eb0a9c963 , < 2a5ac0c0f1f7da33929211a2e41911bf72ee35d8 (git)
Affected: 4f76617378ee97c557b526cb58d3c61eb0a9c963 , < 34f4feff3e90bd09308fad0974e97113b23b812a (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.2
Unaffected: 0 , < 5.2 (semver)
Unaffected: 5.15.218 , ≤ 5.15.* (semver)
Unaffected: 6.1.185 , ≤ 6.1.* (semver)
Unaffected: 6.6.153 , ≤ 6.6.* (semver)
Unaffected: 6.12.105 , ≤ 6.12.* (semver)
Unaffected: 6.18.46 , ≤ 6.18.* (semver)
Unaffected: 7.1.10 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
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            "drivers/s390/cio/vfio_ccw_private.h"
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              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio_ccw: Selectively expand io_mutex\n\nThe io_mutex was defined to serialize the io_regions, but then has\nalso sort of been associated with the I/O themselves because of\nthe close relationship they share.\n\nWith the handful of races that are possible, the choices are either to:\n A) expand the scope of io_mutex to close these remaining windows, or\n B) reduce the scope of io_mutex to just io_region, and introduce a new\n    lock mechanism for the remaining I/O resources\n\nThis patch implements A, since B brings with it a lot more interactions\nthat would need to be tracked and kept in a correct hierarchy. It also\ntakes advantage of the workqueue element for cp_free() that now gets\ncalled out of fsm_notoper(), which could be invoked out of an interrupt\ncontext and thus cannot acquire a mutex itself."
        }
      ],
      "metrics": [
        {
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
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          "scenarios": [
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              "lang": "en",
              "value": "AV:L - The bug is reached only through local VFIO mediated-device syscalls (read/write/ioctl on vfio-ccw device fds) and deferred work from hardware I/O interrupts and channel-path events; vfio-ccw has no network, Bluetooth, or physical-bus entry point.\nAC:L - The VFIO client controls both sides of each race window: it can submit channel I/O, close or reset the device, and trigger DMA unmap while io_work, notoper_work, or fsm_close concurrently run cp_free, cp_update_scsw, or cp_iova_pinned without full io_mutex protection, and retry to win reliably.\nPR:L - Exploitation requires an opened vfio-ccw mdev device fd (typical QEMU/libvirt VM operator or delegated /dev/vfio holder on IBM Z passthrough hosts), not init-namespace root; mdev creation is admin setup, but triggering the races needs only that delegated VFIO client access.\nUI:N - No separate victim action is required; once vfio-ccw passthrough is configured, the attacker issues concurrent channel I/O, region access, device close/reset, or DMA unmap without needing another user to mount media or interact.\nS:C - On IBM Z/LinuxONE, vfio-ccw passes DASD/CCW subchannels into KVM guests; guest-driven channel I/O and path events trigger host interrupt/workqueue activity concurrent with VFIO client teardown, corrupting hypervisor kernel memory outside the VM security boundary.\nC:H - cp_free racing with cp_update_scsw, cp_iova_pinned, and io_region access without io_mutex causes use-after-free on ccwchain_list and page_array structures; per kernel UAF guidance this enables attacker-influenced heap reuse and arbitrary kernel read primitives.\nI:H - Concurrent cp_free during cp_init, page_array_unpin_free, memcpy into io_region, and mutex operations on freed channel_program memory provides heap-sprayable arbitrary write and control-flow hijack potential beyond a simple crash.\nA:H - Use-after-free and double-free of channel program structures during concurrent I/O completion, not-operational cleanup, or device close can immediately oops or panic the host kernel from invalid list/mutex access, and successful exploitation can crash or hang the system."
            }
          ]
        }
      ],
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        "dateUpdated": "2026-08-27T12:40:08.507Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80548",
    "datePublished": "2026-08-26T14:37:18.759Z",
    "dateReserved": "2026-08-26T14:34:25.766Z",
    "dateUpdated": "2026-08-27T12:40:08.507Z",
    "state": "PUBLISHED"
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  "dataVersion": "5.2",
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      "date": "2026-09-01",
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It also\\ntakes advantage of the workqueue element for cp_free() that now gets\\ncalled out of fsm_notoper(), which could be invoked out of an interrupt\\ncontext and thus cannot acquire a mutex itself.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/s390/cio/vfio_ccw_chp.c\",\"drivers/s390/cio/vfio_ccw_cp.c\",\"drivers/s390/cio/vfio_ccw_drv.c\",\"drivers/s390/cio/vfio_ccw_fsm.c\",\"drivers/s390/cio/vfio_ccw_private.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4f76617378ee97c557b526cb58d3c61eb0a9c963\",\"lessThan\":\"dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"4f76617378ee97c557b526cb58d3c61eb0a9c963\",\"lessThan\":\"56d7488533ceac4e986e96e15c9e487a2245bc01\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"4f76617378ee97c557b526cb58d3c61eb0a9c963\",\"lessThan\":\"f72a51810d49411bd8cad0c2df8592320a2fe5cc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"4f76617378ee97c557b526cb58d3c61eb0a9c963\",\"lessThan\":\"2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"4f76617378ee97c557b526cb58d3c61eb0a9c963\",\"lessThan\":\"b6aecea4b2b246f9fbd98a5712daa1193a60818e\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"4f76617378ee97c557b526cb58d3c61eb0a9c963\",\"lessThan\":\"2a5ac0c0f1f7da33929211a2e41911bf72ee35d8\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"4f76617378ee97c557b526cb58d3c61eb0a9c963\",\"lessThan\":\"34f4feff3e90bd09308fad0974e97113b23b812a\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/s390/cio/vfio_ccw_chp.c\",\"drivers/s390/cio/vfio_ccw_cp.c\",\"drivers/s390/cio/vfio_ccw_drv.c\",\"drivers/s390/cio/vfio_ccw_fsm.c\",\"drivers/s390/cio/vfio_ccw_private.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.2\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.2\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.218\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.185\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.153\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.105\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.46\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.10\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H\",\"baseScore\":8.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.0,\"impactScore\":6.0}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/2a5ac0c0f1f7da33929211a2e41911bf72ee35d8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/34f4feff3e90bd09308fad0974e97113b23b812a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/56d7488533ceac4e986e96e15c9e487a2245bc01\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b6aecea4b2b246f9fbd98a5712daa1193a60818e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f72a51810d49411bd8cad0c2df8592320a2fe5cc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-27T14:54:58+00:00",
      "cve": "CVE-2026-80548",
      "id": "CVE-2026-80548",
      "initial_release_date": "2026-08-26T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: s390/vfio_ccw: Selectively expand io_mutex",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80548.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.