CVE-2026-80548 (GCVE-0-2026-80548)
Vulnerability from cvelistv5
Published
2026-08-26 14:37
Modified
2026-08-27 12:40
Severity ?
VLAI Severity ?
EPSS score ?
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.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 4f76617378ee97c557b526cb58d3c61eb0a9c963 Version: 4f76617378ee97c557b526cb58d3c61eb0a9c963 Version: 4f76617378ee97c557b526cb58d3c61eb0a9c963 Version: 4f76617378ee97c557b526cb58d3c61eb0a9c963 Version: 4f76617378ee97c557b526cb58d3c61eb0a9c963 Version: 4f76617378ee97c557b526cb58d3c61eb0a9c963 Version: 4f76617378ee97c557b526cb58d3c61eb0a9c963 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"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",
"vendor": "Linux",
"versions": [
{
"lessThan": "dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0",
"status": "affected",
"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963",
"versionType": "git"
},
{
"lessThan": "56d7488533ceac4e986e96e15c9e487a2245bc01",
"status": "affected",
"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963",
"versionType": "git"
},
{
"lessThan": "f72a51810d49411bd8cad0c2df8592320a2fe5cc",
"status": "affected",
"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963",
"versionType": "git"
},
{
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"status": "affected",
"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963",
"versionType": "git"
},
{
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"status": "affected",
"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963",
"versionType": "git"
},
{
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"status": "affected",
"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963",
"versionType": "git"
},
{
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"status": "affected",
"version": "4f76617378ee97c557b526cb58d3c61eb0a9c963",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"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",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.2"
},
{
"lessThan": "5.2",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.218",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.185",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.153",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.105",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.46",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.10",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.218",
"versionStartIncluding": "5.2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.185",
"versionStartIncluding": "5.2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.153",
"versionStartIncluding": "5.2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.105",
"versionStartIncluding": "5.2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.46",
"versionStartIncluding": "5.2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.10",
"versionStartIncluding": "5.2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "5.2",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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": [
{
"cvssV3_1": {
"baseScore": 8.8,
"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"
},
"scenarios": [
{
"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."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-27T12:40:08.507Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/dab6a6627b0b0cce23653e99c7b0bf8c6cfd82e0"
},
{
"url": "https://git.kernel.org/stable/c/56d7488533ceac4e986e96e15c9e487a2245bc01"
},
{
"url": "https://git.kernel.org/stable/c/f72a51810d49411bd8cad0c2df8592320a2fe5cc"
},
{
"url": "https://git.kernel.org/stable/c/2ba9efdf9ebedc4e54df4b56aa3b43a65f7967cd"
},
{
"url": "https://git.kernel.org/stable/c/b6aecea4b2b246f9fbd98a5712daa1193a60818e"
},
{
"url": "https://git.kernel.org/stable/c/2a5ac0c0f1f7da33929211a2e41911bf72ee35d8"
},
{
"url": "https://git.kernel.org/stable/c/34f4feff3e90bd09308fad0974e97113b23b812a"
}
],
"title": "s390/vfio_ccw: Selectively expand io_mutex",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"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"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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