CVE-2026-31667 (GCVE-0-2026-31667)
Vulnerability from cvelistv5 – Published: 2026-04-24 14:45 – Updated: 2026-08-05 12:24
VLAI
EPSS
VEX
Title
Input: uinput - fix circular locking dependency with ff-core
Summary
In the Linux kernel, the following vulnerability has been resolved:
Input: uinput - fix circular locking dependency with ff-core
A lockdep circular locking dependency warning can be triggered
reproducibly when using a force-feedback gamepad with uinput (for
example, playing ELDEN RING under Wine with a Flydigi Vader 5
controller):
ff->mutex -> udev->mutex -> input_mutex -> dev->mutex -> ff->mutex
The cycle is caused by four lock acquisition paths:
1. ff upload: input_ff_upload() holds ff->mutex and calls
uinput_dev_upload_effect() -> uinput_request_submit() ->
uinput_request_send(), which acquires udev->mutex.
2. device create: uinput_ioctl_handler() holds udev->mutex and calls
uinput_create_device() -> input_register_device(), which acquires
input_mutex.
3. device register: input_register_device() holds input_mutex and
calls kbd_connect() -> input_register_handle(), which acquires
dev->mutex.
4. evdev release: evdev_release() calls input_flush_device() under
dev->mutex, which calls input_ff_flush() acquiring ff->mutex.
Fix this by introducing a new state_lock spinlock to protect
udev->state and udev->dev access in uinput_request_send() instead of
acquiring udev->mutex. The function only needs to atomically check
device state and queue an input event into the ring buffer via
uinput_dev_event() -- both operations are safe under a spinlock
(ktime_get_ts64() and wake_up_interruptible() do not sleep). This
breaks the ff->mutex -> udev->mutex link since a spinlock is a leaf in
the lock ordering and cannot form cycles with mutexes.
To keep state transitions visible to uinput_request_send(), protect
writes to udev->state in uinput_create_device() and
uinput_destroy_device() with the same state_lock spinlock.
Additionally, move init_completion(&request->done) from
uinput_request_send() to uinput_request_submit() before
uinput_request_reserve_slot(). Once the slot is allocated,
uinput_flush_requests() may call complete() on it at any time from
the destroy path, so the completion must be initialised before the
request becomes visible.
Lock ordering after the fix:
ff->mutex -> state_lock (spinlock, leaf)
udev->mutex -> state_lock (spinlock, leaf)
udev->mutex -> input_mutex -> dev->mutex -> ff->mutex (no back-edge)
Severity
7.8 (High)
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
ff462551235d8d7d843a005950bc90924fcedede , < 71a9729f412e2c692a35c542e14b706fb342927f
(git)
Affected: ff462551235d8d7d843a005950bc90924fcedede , < 271ee71a1917b89f6d73ec82dd091c33d92ee617 (git) Affected: ff462551235d8d7d843a005950bc90924fcedede , < 974f7b138c3a96dd5cd53d1b33409cd7b2229dc6 (git) Affected: ff462551235d8d7d843a005950bc90924fcedede , < 546c18a14924eb521fe168d916d7ce28f1e13c1d (git) Affected: ff462551235d8d7d843a005950bc90924fcedede , < a3d6c9c053c9c605651508569230ead633b13f76 (git) Affected: ff462551235d8d7d843a005950bc90924fcedede , < 1e09dfbb4f5d20ee111f92325a00f85778a5f328 (git) Affected: ff462551235d8d7d843a005950bc90924fcedede , < 1534661043c434b81cfde26b97a2fb2460329cf0 (git) Affected: ff462551235d8d7d843a005950bc90924fcedede , < 4cda78d6f8bf2b700529f2fbccb994c3e826d7c2 (git) |
guessed | |
| Linux | Linux |
Affected:
2.6.19
Unaffected: 0 , < 2.6.19 (semver) Unaffected: 5.10.253 , ≤ 5.10.* (semver) Unaffected: 5.15.203 , ≤ 5.15.* (semver) Unaffected: 6.1.169 , ≤ 6.1.* (semver) Unaffected: 6.6.135 , ≤ 6.6.* (semver) Unaffected: 6.12.82 , ≤ 6.12.* (semver) Unaffected: 6.18.23 , ≤ 6.18.* (semver) Unaffected: 6.19.13 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix) |
guessed |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nInput: uinput - fix circular locking dependency with ff-core\n\nA lockdep circular locking dependency warning can be triggered\nreproducibly when using a force-feedback gamepad with uinput (for\nexample, playing ELDEN RING under Wine with a Flydigi Vader 5\ncontroller):\n\n ff-\u003emutex -\u003e udev-\u003emutex -\u003e input_mutex -\u003e dev-\u003emutex -\u003e ff-\u003emutex\n\nThe cycle is caused by four lock acquisition paths:\n\n1. ff upload: input_ff_upload() holds ff-\u003emutex and calls\n uinput_dev_upload_effect() -\u003e uinput_request_submit() -\u003e\n uinput_request_send(), which acquires udev-\u003emutex.\n\n2. device create: uinput_ioctl_handler() holds udev-\u003emutex and calls\n uinput_create_device() -\u003e input_register_device(), which acquires\n input_mutex.\n\n3. device register: input_register_device() holds input_mutex and\n calls kbd_connect() -\u003e input_register_handle(), which acquires\n dev-\u003emutex.\n\n4. evdev release: evdev_release() calls input_flush_device() under\n dev-\u003emutex, which calls input_ff_flush() acquiring ff-\u003emutex.\n\nFix this by introducing a new state_lock spinlock to protect\nudev-\u003estate and udev-\u003edev access in uinput_request_send() instead of\nacquiring udev-\u003emutex. The function only needs to atomically check\ndevice state and queue an input event into the ring buffer via\nuinput_dev_event() -- both operations are safe under a spinlock\n(ktime_get_ts64() and wake_up_interruptible() do not sleep). This\nbreaks the ff-\u003emutex -\u003e udev-\u003emutex link since a spinlock is a leaf in\nthe lock ordering and cannot form cycles with mutexes.\n\nTo keep state transitions visible to uinput_request_send(), protect\nwrites to udev-\u003estate in uinput_create_device() and\nuinput_destroy_device() with the same state_lock spinlock.\n\nAdditionally, move init_completion(\u0026request-\u003edone) from\nuinput_request_send() to uinput_request_submit() before\nuinput_request_reserve_slot(). Once the slot is allocated,\nuinput_flush_requests() may call complete() on it at any time from\nthe destroy path, so the completion must be initialised before the\nrequest becomes visible.\n\nLock ordering after the fix:\n\n ff-\u003emutex -\u003e state_lock (spinlock, leaf)\n udev-\u003emutex -\u003e state_lock (spinlock, leaf)\n udev-\u003emutex -\u003e input_mutex -\u003e dev-\u003emutex -\u003e ff-\u003emutex (no back-edge)"
}
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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"lang": "en",
"value": "AV:L - The vulnerable code is reached through local uinput and evdev character-device operations, including uinput setup/destruction ioctls and evdev force-feedback upload ioctls. There is no network, adjacent, or physical packet/device insertion path.\nAC:L - The attacker can control the relevant operations by creating a force-feedback uinput device and racing/concurrently invoking force-feedback upload and device teardown paths. Because both sides of the race are attacker-driven, the complexity is Low.\nPR:L - The kernel code does not require CAP_SYS_ADMIN or another capability, but the attacker needs local access to the uinput/evdev device nodes. In the most severe reasonable deployments these are reachable by an unprivileged local user or input/session-privileged account, so this is Low rather than High.\nUI:N - No victim action is required once the attacker has local device-node access. The attacker can issue the needed ioctls and close/release operations directly.\nS:U - The impact remains within the local kernel/input subsystem security authority. This is not a VM escape, IOMMU bypass, or other cross-scope boundary violation.\nC:H - The fix includes moving completion initialization before publishing the request slot, because teardown could otherwise call complete() on an uninitialized stack completion. That is kernel memory corruption, and under the required higher-severity rule it is treated as potentially enabling kernel memory disclosure.\nI:H - Calling complete() on an uninitialized completion can operate on corrupted spinlock/list state and kernel pointers, not merely return an error. Under the required higher-severity rule, this memory corruption is scored as potentially enabling high-integrity kernel compromise.\nA:H - The documented locking cycle can deadlock, and the uninitialized completion race is consistent with prior uinput force-feedback crashes involving bad spinlock state. Either outcome can hang or crash the kernel, so availability impact is High."
}
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"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*",
"matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*",
"matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*",
"matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*",
"matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*",
"matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*",
"matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nInput: uinput - fix circular locking dependency with ff-core\n\nA lockdep circular locking dependency warning can be triggered\nreproducibly when using a force-feedback gamepad with uinput (for\nexample, playing ELDEN RING under Wine with a Flydigi Vader 5\ncontroller):\n\n ff-\u003emutex -\u003e udev-\u003emutex -\u003e input_mutex -\u003e dev-\u003emutex -\u003e ff-\u003emutex\n\nThe cycle is caused by four lock acquisition paths:\n\n1. ff upload: input_ff_upload() holds ff-\u003emutex and calls\n uinput_dev_upload_effect() -\u003e uinput_request_submit() -\u003e\n uinput_request_send(), which acquires udev-\u003emutex.\n\n2. device create: uinput_ioctl_handler() holds udev-\u003emutex and calls\n uinput_create_device() -\u003e input_register_device(), which acquires\n input_mutex.\n\n3. device register: input_register_device() holds input_mutex and\n calls kbd_connect() -\u003e input_register_handle(), which acquires\n dev-\u003emutex.\n\n4. evdev release: evdev_release() calls input_flush_device() under\n dev-\u003emutex, which calls input_ff_flush() acquiring ff-\u003emutex.\n\nFix this by introducing a new state_lock spinlock to protect\nudev-\u003estate and udev-\u003edev access in uinput_request_send() instead of\nacquiring udev-\u003emutex. The function only needs to atomically check\ndevice state and queue an input event into the ring buffer via\nuinput_dev_event() -- both operations are safe under a spinlock\n(ktime_get_ts64() and wake_up_interruptible() do not sleep). This\nbreaks the ff-\u003emutex -\u003e udev-\u003emutex link since a spinlock is a leaf in\nthe lock ordering and cannot form cycles with mutexes.\n\nTo keep state transitions visible to uinput_request_send(), protect\nwrites to udev-\u003estate in uinput_create_device() and\nuinput_destroy_device() with the same state_lock spinlock.\n\nAdditionally, move init_completion(\u0026request-\u003edone) from\nuinput_request_send() to uinput_request_submit() before\nuinput_request_reserve_slot(). Once the slot is allocated,\nuinput_flush_requests() may call complete() on it at any time from\nthe destroy path, so the completion must be initialised before the\nrequest becomes visible.\n\nLock ordering after the fix:\n\n ff-\u003emutex -\u003e state_lock (spinlock, leaf)\n udev-\u003emutex -\u003e state_lock (spinlock, leaf)\n udev-\u003emutex -\u003e input_mutex -\u003e dev-\u003emutex -\u003e ff-\u003emutex (no back-edge)"
}
],
"id": "CVE-2026-31667",
"lastModified": "2026-06-17T10:34:11.923",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-04-24T15:16:46.390",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/1534661043c434b81cfde26b97a2fb2460329cf0"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/1e09dfbb4f5d20ee111f92325a00f85778a5f328"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/271ee71a1917b89f6d73ec82dd091c33d92ee617"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/4cda78d6f8bf2b700529f2fbccb994c3e826d7c2"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/546c18a14924eb521fe168d916d7ce28f1e13c1d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/71a9729f412e2c692a35c542e14b706fb342927f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/974f7b138c3a96dd5cd53d1b33409cd7b2229dc6"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/a3d6c9c053c9c605651508569230ead633b13f76"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-667"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-07-02T17:15:03+00:00",
"cve": "CVE-2026-31667",
"id": "CVE-2026-31667",
"initial_release_date": "2026-04-24T00:00:00+00:00",
"product_status:known_affected": "260",
"product_status:known_not_affected": "14",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: Input: uinput - fix circular locking dependency with ff-core",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31667.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-08-28T01:27:57Z",
"cve": "CVE-2026-31667",
"id": "CVE-2026-31667",
"initial_release_date": "2026-04-25T01:36:34Z",
"product_status:first_fixed": "2",
"product_status:known_affected": "595",
"product_status:known_not_affected": "15",
"product_status:recommended": "302",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-31667",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-31667.json",
"version": "11"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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
| Author | Source | Type | Date | Other |
|---|
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.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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