CVE-2022-48943 (GCVE-0-2022-48943)
Vulnerability from cvelistv5 – Published: 2024-08-22 03:30 – Updated: 2026-08-05 08:53
VLAI
EPSS
VEX
Title
KVM: x86/mmu: make apf token non-zero to fix bug
Summary
In the Linux kernel, the following vulnerability has been resolved:
KVM: x86/mmu: make apf token non-zero to fix bug
In current async pagefault logic, when a page is ready, KVM relies on
kvm_arch_can_dequeue_async_page_present() to determine whether to deliver
a READY event to the Guest. This function test token value of struct
kvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a
READY event is finished by Guest. If value is zero meaning that a READY
event is done, so the KVM can deliver another.
But the kvm_arch_setup_async_pf() may produce a valid token with zero
value, which is confused with previous mention and may lead the loss of
this READY event.
This bug may cause task blocked forever in Guest:
INFO: task stress:7532 blocked for more than 1254 seconds.
Not tainted 5.10.0 #16
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:stress state:D stack: 0 pid: 7532 ppid: 1409
flags:0x00000080
Call Trace:
__schedule+0x1e7/0x650
schedule+0x46/0xb0
kvm_async_pf_task_wait_schedule+0xad/0xe0
? exit_to_user_mode_prepare+0x60/0x70
__kvm_handle_async_pf+0x4f/0xb0
? asm_exc_page_fault+0x8/0x30
exc_page_fault+0x6f/0x110
? asm_exc_page_fault+0x8/0x30
asm_exc_page_fault+0x1e/0x30
RIP: 0033:0x402d00
RSP: 002b:00007ffd31912500 EFLAGS: 00010206
RAX: 0000000000071000 RBX: ffffffffffffffff RCX: 00000000021a32b0
RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0
RBP: 00000000021262b0 R08: 0000000000000003 R09: 0000000000000086
R10: 00000000000000eb R11: 00007fefbdf2baa0 R12: 0000000000000000
R13: 0000000000000002 R14: 000000000007d000 R15: 0000000000001000
Severity
7.1 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-09-10 15:33 UTC
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
2635b5c4a0e407b84f68e188c719f28ba0e9ae1b , < 72fdfc75d4217b32363cc80def3de2cb3fef3f02
(git)
Affected: 2635b5c4a0e407b84f68e188c719f28ba0e9ae1b , < 4c3644b6c96c5daa5149e5abddc07234eea47c7c (git) Affected: 2635b5c4a0e407b84f68e188c719f28ba0e9ae1b , < 62040f5cd7d937de547836e747b6aa8212fec573 (git) Affected: 2635b5c4a0e407b84f68e188c719f28ba0e9ae1b , < 6f3c1fc53d86d580d8d6d749c4af23705e4f6f79 (git) |
guessed | |
| Linux | Linux |
Affected:
5.8
Unaffected: 0 , < 5.8 (semver) Unaffected: 5.10.103 , ≤ 5.10.* (semver) Unaffected: 5.15.26 , ≤ 5.15.* (semver) Unaffected: 5.16.12 , ≤ 5.16.* (semver) Unaffected: 5.17 , ≤ * (original_commit_for_fix) |
guessed |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86/mmu: make apf token non-zero to fix bug\n\nIn current async pagefault logic, when a page is ready, KVM relies on\nkvm_arch_can_dequeue_async_page_present() to determine whether to deliver\na READY event to the Guest. This function test token value of struct\nkvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a\nREADY event is finished by Guest. If value is zero meaning that a READY\nevent is done, so the KVM can deliver another.\nBut the kvm_arch_setup_async_pf() may produce a valid token with zero\nvalue, which is confused with previous mention and may lead the loss of\nthis READY event.\n\nThis bug may cause task blocked forever in Guest:\n INFO: task stress:7532 blocked for more than 1254 seconds.\n Not tainted 5.10.0 #16\n \"echo 0 \u003e /proc/sys/kernel/hung_task_timeout_secs\" disables this message.\n task:stress state:D stack: 0 pid: 7532 ppid: 1409\n flags:0x00000080\n Call Trace:\n __schedule+0x1e7/0x650\n schedule+0x46/0xb0\n kvm_async_pf_task_wait_schedule+0xad/0xe0\n ? exit_to_user_mode_prepare+0x60/0x70\n __kvm_handle_async_pf+0x4f/0xb0\n ? asm_exc_page_fault+0x8/0x30\n exc_page_fault+0x6f/0x110\n ? asm_exc_page_fault+0x8/0x30\n asm_exc_page_fault+0x1e/0x30\n RIP: 0033:0x402d00\n RSP: 002b:00007ffd31912500 EFLAGS: 00010206\n RAX: 0000000000071000 RBX: ffffffffffffffff RCX: 00000000021a32b0\n RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0\n RBP: 00000000021262b0 R08: 0000000000000003 R09: 0000000000000086\n R10: 00000000000000eb R11: 00007fefbdf2baa0 R12: 0000000000000000\n R13: 0000000000000002 R14: 000000000007d000 R15: 0000000000001000"
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"value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: KVM: x86/mmu: haga que el token apf sea distinto de cero para corregir el error En la l\u00f3gica de error de p\u00e1gina as\u00edncrona actual, cuando una p\u00e1gina est\u00e1 lista, KVM se basa en kvm_arch_can_dequeue_async_page_present() para determinar si se debe entregar un evento LISTO para el Invitado. Esta funci\u00f3n prueba el valor del token de la estructura kvm_vcpu_pv_apf_data, que el kernel invitado debe restablecer a cero cuando el invitado finaliza un evento READY. Si el valor es cero, significa que se realiz\u00f3 un evento READY, por lo que el KVM puede entregar otro. Pero kvm_arch_setup_async_pf() puede producir un token v\u00e1lido con valor cero, lo que se confunde con la menci\u00f3n anterior y puede provocar la p\u00e9rdida de este evento READY. Este error puede causar que la tarea se bloquee para siempre en Guest: INFORMACI\u00d3N: tarea de estr\u00e9s:7532 bloqueada durante m\u00e1s de 1254 segundos. Not tainted 5.10.0 #16 \"echo 0 \u0026gt; /proc/sys/kernel/hung_task_timeout_secs\" desactiva este mensaje. tarea:estr\u00e9s estado:D pila: 0 pid: 7532 ppid: 1409 banderas:0x00000080 Seguimiento de llamadas: __schedule+0x1e7/0x650 Schedule+0x46/0xb0 kvm_async_pf_task_wait_schedule+0xad/0xe0 ? exit_to_user_mode_prepare+0x60/0x70 __kvm_handle_async_pf+0x4f/0xb0 ? asm_exc_page_fault+0x8/0x30 exc_page_fault+0x6f/0x110? asm_exc_page_fault+0x8/0x30 asm_exc_page_fault+0x1e/0x30 RIP: 0033:0x402d00 RSP: 002b:00007ffd31912500 EFLAGS: 00010206 RAX: 0000000000071000 RBX: ffffffff RCX: 00000000021a32b0 RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0 RBP: 00000000021262b0 R08: 03 R09: 0000000000000086 R10: 000000000000000000EB R11: 00007FEFBDF2BAA0 R12: 00000000000000000000 R13: 0000000000000002 R14: 000000000007D000 R15: 00000000001000"
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"url": "https://git.kernel.org/stable/c/6f3c1fc53d86d580d8d6d749c4af23705e4f6f79"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/72fdfc75d4217b32363cc80def3de2cb3fef3f02"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Modified",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "NVD-CWE-noinfo"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-08-04T19:47:28+00:00",
"cve": "CVE-2022-48943",
"id": "CVE-2022-48943",
"initial_release_date": "2022-01-01T00:00:00+00:00",
"product_status:fixed": "581",
"product_status:known_affected": "38",
"product_status:known_not_affected": "42",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: KVM: x86/mmu: make apf token non-zero to fix bug",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2022/cve-2022-48943.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2022-48943",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2024-09-10T15:33:08.943998Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2024-09-11T12:42:15.638Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"arch/x86/kvm/mmu/mmu.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "72fdfc75d4217b32363cc80def3de2cb3fef3f02",
"status": "affected",
"version": "2635b5c4a0e407b84f68e188c719f28ba0e9ae1b",
"versionType": "git"
},
{
"lessThan": "4c3644b6c96c5daa5149e5abddc07234eea47c7c",
"status": "affected",
"version": "2635b5c4a0e407b84f68e188c719f28ba0e9ae1b",
"versionType": "git"
},
{
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"status": "affected",
"version": "2635b5c4a0e407b84f68e188c719f28ba0e9ae1b",
"versionType": "git"
},
{
"lessThan": "6f3c1fc53d86d580d8d6d749c4af23705e4f6f79",
"status": "affected",
"version": "2635b5c4a0e407b84f68e188c719f28ba0e9ae1b",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"arch/x86/kvm/mmu/mmu.c"
],
"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": "5.10.*",
"status": "unaffected",
"version": "5.10.103",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.26",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.16.*",
"status": "unaffected",
"version": "5.16.12",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "5.17",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.103",
"versionStartIncluding": "5.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.26",
"versionStartIncluding": "5.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"vulnerable": true
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{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "5.8",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86/mmu: make apf token non-zero to fix bug\n\nIn current async pagefault logic, when a page is ready, KVM relies on\nkvm_arch_can_dequeue_async_page_present() to determine whether to deliver\na READY event to the Guest. This function test token value of struct\nkvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a\nREADY event is finished by Guest. If value is zero meaning that a READY\nevent is done, so the KVM can deliver another.\nBut the kvm_arch_setup_async_pf() may produce a valid token with zero\nvalue, which is confused with previous mention and may lead the loss of\nthis READY event.\n\nThis bug may cause task blocked forever in Guest:\n INFO: task stress:7532 blocked for more than 1254 seconds.\n Not tainted 5.10.0 #16\n \"echo 0 \u003e /proc/sys/kernel/hung_task_timeout_secs\" disables this message.\n task:stress state:D stack: 0 pid: 7532 ppid: 1409\n flags:0x00000080\n Call Trace:\n __schedule+0x1e7/0x650\n schedule+0x46/0xb0\n kvm_async_pf_task_wait_schedule+0xad/0xe0\n ? exit_to_user_mode_prepare+0x60/0x70\n __kvm_handle_async_pf+0x4f/0xb0\n ? asm_exc_page_fault+0x8/0x30\n exc_page_fault+0x6f/0x110\n ? asm_exc_page_fault+0x8/0x30\n asm_exc_page_fault+0x1e/0x30\n RIP: 0033:0x402d00\n RSP: 002b:00007ffd31912500 EFLAGS: 00010206\n RAX: 0000000000071000 RBX: ffffffffffffffff RCX: 00000000021a32b0\n RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0\n RBP: 00000000021262b0 R08: 0000000000000003 R09: 0000000000000086\n R10: 00000000000000eb R11: 00007fefbdf2baa0 R12: 0000000000000000\n R13: 0000000000000002 R14: 000000000007d000 R15: 0000000000001000"
}
],
"metrics": [
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"baseScore": 7.1,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The bug is reached only when a KVM guest takes a paravirtual async page fault (KVM_RUN \u2192 faultin \u2192 kvm_arch_setup_async_pf), which requires local code execution inside a VM or local /dev/kvm use\u2014not remote packet processing.\nAC:L - On overcommitted KVM hosts (common cloud deployments) async PF is routinely exercised; token 0 is produced deterministically on vCPU 0 when (id\u003c\u003c12)==0, and concurrent READY completions that drop that event are driven by attacker/workload-controlled multi-threaded memory stress, as in the original hang report.\nPR:N - No host privileges are required\u2014an ordinary tenant VM triggers this via normal guest userspace page faults after the guest kernel enables MSR_KVM_ASYNC_PF_EN, matching other guest-triggerable KVM DoS scores (PR:N relative to the host).\nUI:N - No separate victim action is needed; guest memory accesses under host reclaim/async PF delivery alone hit the vulnerable token path.\nS:C - The vulnerable code is host KVM MMU/async-PF handling, but the impact is permanent denial of guest task/VM progress across the hypervisor\u2013guest (and nested L1/L2) security boundary, consistent with other host-KVM guest-availability DoS scorings.\nC:N - This is solely a confused zero token versus the READY-slot-empty sentinel causing a lost wakeup; there is no OOB read, UAF, or other disclosure primitive.\nI:N - No memory corruption, write primitive, or control-flow hijack occurs\u2014only failure to deliver a READY notification for a valid token value of zero.\nA:H - A lost READY leaves the guest task blocked forever in TASK_UNINTERRUPTIBLE (D state), which is a complete denial of that workload\u2019s availability and can stall nested guests depending on the hung threads."
}
]
}
],
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"references": [
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"url": "https://git.kernel.org/stable/c/72fdfc75d4217b32363cc80def3de2cb3fef3f02"
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{
"url": "https://git.kernel.org/stable/c/4c3644b6c96c5daa5149e5abddc07234eea47c7c"
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"url": "https://git.kernel.org/stable/c/62040f5cd7d937de547836e747b6aa8212fec573"
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{
"url": "https://git.kernel.org/stable/c/6f3c1fc53d86d580d8d6d749c4af23705e4f6f79"
}
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"title": "KVM: x86/mmu: make apf token non-zero to fix bug",
"x_generator": {
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"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2022-48943",
"datePublished": "2024-08-22T03:30:14.027Z",
"dateReserved": "2024-08-22T01:27:53.623Z",
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"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
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}
}
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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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