CVE-2021-4454 (GCVE-0-2021-4454)
Vulnerability from cvelistv5 – Published: 2025-03-27 16:37 – Updated: 2026-10-15 21:21
VLAI
EPSS
VEX
Title
can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate
Summary
In the Linux kernel, the following vulnerability has been resolved:
can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate
The conclusion "j1939_session_deactivate() should be called with a
session ref-count of at least 2" is incorrect. In some concurrent
scenarios, j1939_session_deactivate can be called with the session
ref-count less than 2. But there is not any problem because it
will check the session active state before session putting in
j1939_session_deactivate_locked().
Here is the concurrent scenario of the problem reported by syzbot
and my reproduction log.
cpu0 cpu1
j1939_xtp_rx_eoma
j1939_xtp_rx_abort_one
j1939_session_get_by_addr [kref == 2]
j1939_session_get_by_addr [kref == 3]
j1939_session_deactivate [kref == 2]
j1939_session_put [kref == 1]
j1939_session_completed
j1939_session_deactivate
WARN_ON_ONCE(kref < 2)
=====================================================
WARNING: CPU: 1 PID: 21 at net/can/j1939/transport.c:1088 j1939_session_deactivate+0x5f/0x70
CPU: 1 PID: 21 Comm: ksoftirqd/1 Not tainted 5.14.0-rc7+ #32
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
RIP: 0010:j1939_session_deactivate+0x5f/0x70
Call Trace:
j1939_session_deactivate_activate_next+0x11/0x28
j1939_xtp_rx_eoma+0x12a/0x180
j1939_tp_recv+0x4a2/0x510
j1939_can_recv+0x226/0x380
can_rcv_filter+0xf8/0x220
can_receive+0x102/0x220
? process_backlog+0xf0/0x2c0
can_rcv+0x53/0xf0
__netif_receive_skb_one_core+0x67/0x90
? process_backlog+0x97/0x2c0
__netif_receive_skb+0x22/0x80
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-15 21:02 UTC
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
7eef18c0479ba5d9f54fba30cd77c233ebca3eb1 , < 6950df42a03c9ac9290503ced3f371199cb68fa9
(git)
Affected: 55dd22c5d029423f513fd849e633adf0e9c10d0c , < b6d44072117bba057d50f7a2f96e5d070c65926d (git) Affected: 0c71437dd50dd687c15d8ca80b3b68f10bb21d63 , < 9ab896775f98ff54b68512f345eed178bf961084 (git) Affected: 0c71437dd50dd687c15d8ca80b3b68f10bb21d63 , < 1740a1e45eee65099a92fb502e1e67e63aad277d (git) Affected: 0c71437dd50dd687c15d8ca80b3b68f10bb21d63 , < d0553680f94c49bbe0e39eb50d033ba563b4212d (git) Affected: 5e1fc537c1be332aef9621ca9146aeb3ba59522f (git) Affected: 5.4.138 , < 5.4.232 (semver) Affected: 5.10.56 , < 5.10.168 (semver) Affected: 5.13.8 , < 5.14 (semver) |
guessed | |
| Linux | Linux |
Affected:
5.14
Unaffected: 0 , < 5.14 (semver) Unaffected: 5.4.232 , ≤ 5.4.* (semver) Unaffected: 5.10.168 , ≤ 5.10.* (semver) Unaffected: 5.15.93 , ≤ 5.15.* (semver) Unaffected: 6.1.11 , ≤ 6.1.* (semver) Unaffected: 6.2 , ≤ * (original_commit_for_fix) |
guessed |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate\n\nThe conclusion \"j1939_session_deactivate() should be called with a\nsession ref-count of at least 2\" is incorrect. In some concurrent\nscenarios, j1939_session_deactivate can be called with the session\nref-count less than 2. But there is not any problem because it\nwill check the session active state before session putting in\nj1939_session_deactivate_locked().\n\nHere is the concurrent scenario of the problem reported by syzbot\nand my reproduction log.\n\n cpu0 cpu1\n j1939_xtp_rx_eoma\nj1939_xtp_rx_abort_one\n j1939_session_get_by_addr [kref == 2]\nj1939_session_get_by_addr [kref == 3]\nj1939_session_deactivate [kref == 2]\nj1939_session_put [kref == 1]\n\t\t\t\tj1939_session_completed\n\t\t\t\tj1939_session_deactivate\n\t\t\t\tWARN_ON_ONCE(kref \u003c 2)\n\n=====================================================\nWARNING: CPU: 1 PID: 21 at net/can/j1939/transport.c:1088 j1939_session_deactivate+0x5f/0x70\nCPU: 1 PID: 21 Comm: ksoftirqd/1 Not tainted 5.14.0-rc7+ #32\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014\nRIP: 0010:j1939_session_deactivate+0x5f/0x70\nCall Trace:\n j1939_session_deactivate_activate_next+0x11/0x28\n j1939_xtp_rx_eoma+0x12a/0x180\n j1939_tp_recv+0x4a2/0x510\n j1939_can_recv+0x226/0x380\n can_rcv_filter+0xf8/0x220\n can_receive+0x102/0x220\n ? process_backlog+0xf0/0x2c0\n can_rcv+0x53/0xf0\n __netif_receive_skb_one_core+0x67/0x90\n ? process_backlog+0x97/0x2c0\n __netif_receive_skb+0x22/0x80"
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: can: j1939: correcci\u00f3n del error WARN_ON_ONCE en j1939_session_deactivate. La conclusi\u00f3n \"j1939_session_deactivate() debe llamarse con un recuento de referencias de sesi\u00f3n de al menos 2\" es incorrecta. En algunos escenarios concurrentes, se puede llamar a j1939_session_deactivate con un recuento de referencias de sesi\u00f3n inferior a 2. Sin embargo, no hay problema, ya que comprueba el estado activo de la sesi\u00f3n antes de que se active j1939_session_deactivate_locked(). A continuaci\u00f3n, se muestra el escenario concurrente del problema reportado por syzbot y mi registro de reproducci\u00f3n. cpu0 cpu1 j1939_xtp_rx_eoma j1939_xtp_rx_abort_one j1939_session_get_by_addr [kref == 2] j1939_session_get_by_addr [kref == 3] j1939_session_deactivate [kref == 2] j1939_session_put [kref == 1] j1939_session_completed j1939_session_deactivate WARN_ON_ONCE(kref \u0026lt; 2) ======================================================= ADVERTENCIA: CPU: 1 PID: 21 at net/can/j1939/transport.c:1088 j1939_session_deactivate+0x5f/0x70 CPU: 1 PID: 21 Comm: ksoftirqd/1 Not tainted 5.14.0-rc7+ #32 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014 RIP: 0010:j1939_session_deactivate+0x5f/0x70 Call Trace: j1939_session_deactivate_activate_next+0x11/0x28 j1939_xtp_rx_eoma+0x12a/0x180 j1939_tp_recv+0x4a2/0x510 j1939_can_recv+0x226/0x380 can_rcv_filter+0xf8/0x220 can_receive+0x102/0x220 ? process_backlog+0xf0/0x2c0 can_rcv+0x53/0xf0 __netif_receive_skb_one_core+0x67/0x90 ? process_backlog+0x97/0x2c0 __netif_receive_skb+0x22/0x80 "
}
],
"id": "CVE-2021-4454",
"lastModified": "2026-10-15T22:17:22.303",
"metrics": {
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{
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"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
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{
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"integrityImpact": "NONE",
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"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
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],
"role": "CISA Coordinator",
"timestamp": "2026-10-15T21:02:43.206452Z",
"version": "2.0.3"
}
}
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},
"published": "2025-03-27T17:15:35.820",
"references": [
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"initial_release_date": "2021-01-01T00:00:00+00:00",
"product_status:known_affected": "108",
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"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-4454.json",
"version": "3"
},
"vulnrichment": {
"containers": {
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"metrics": [
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"other": {
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"cna": {
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"versions": [
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"descriptions": [
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"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate\n\nThe conclusion \"j1939_session_deactivate() should be called with a\nsession ref-count of at least 2\" is incorrect. In some concurrent\nscenarios, j1939_session_deactivate can be called with the session\nref-count less than 2. But there is not any problem because it\nwill check the session active state before session putting in\nj1939_session_deactivate_locked().\n\nHere is the concurrent scenario of the problem reported by syzbot\nand my reproduction log.\n\n cpu0 cpu1\n j1939_xtp_rx_eoma\nj1939_xtp_rx_abort_one\n j1939_session_get_by_addr [kref == 2]\nj1939_session_get_by_addr [kref == 3]\nj1939_session_deactivate [kref == 2]\nj1939_session_put [kref == 1]\n\t\t\t\tj1939_session_completed\n\t\t\t\tj1939_session_deactivate\n\t\t\t\tWARN_ON_ONCE(kref \u003c 2)\n\n=====================================================\nWARNING: CPU: 1 PID: 21 at net/can/j1939/transport.c:1088 j1939_session_deactivate+0x5f/0x70\nCPU: 1 PID: 21 Comm: ksoftirqd/1 Not tainted 5.14.0-rc7+ #32\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014\nRIP: 0010:j1939_session_deactivate+0x5f/0x70\nCall Trace:\n j1939_session_deactivate_activate_next+0x11/0x28\n j1939_xtp_rx_eoma+0x12a/0x180\n j1939_tp_recv+0x4a2/0x510\n j1939_can_recv+0x226/0x380\n can_rcv_filter+0xf8/0x220\n can_receive+0x102/0x220\n ? process_backlog+0xf0/0x2c0\n can_rcv+0x53/0xf0\n __netif_receive_skb_one_core+0x67/0x90\n ? process_backlog+0x97/0x2c0\n __netif_receive_skb+0x22/0x80"
}
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{
"lang": "en",
"value": "AV:N - The WARN fires on the packet receive path (can_rcv \u2192 j1939_can_recv \u2192 j1939_tp_recv \u2192 j1939_xtp_rx_eoma/abort \u2192 j1939_session_deactivate). An unauthenticated CAN/J1939 peer can trigger it without local code on the target, consistent with other packet-triggered j1939 scores (e.g. CVE-2023-52887, CVE-2026-22997).\nAC:L - The attacker controls both sides of the race by injecting concurrent TP.CM EOMA and Abort frames for the same session; packet content and timing are fully attacker-influenced, so success does not depend on external conditions.\nPR:N - J1939/CAN receive processing has no authentication or credential check; once a legitimate J1939 socket is bound (normal deployment state), an unauthenticated bus peer can inject the crafted frame sequence.\nUI:N - Frames are processed automatically in softirq receive context; no victim or administrator action is required beyond the target already running the J1939 stack.\nS:U - Impact is confined to kernel J1939 session handling within the same host kernel authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:N - The defect is only a spurious WARN_ON_ONCE; the concurrent deactivate path checks session active state before putting, and investigation found no info leak, OOB read, or UAF disclosure primitive.\nI:N - No out-of-bounds write, type confusion, or other integrity/write primitive exists\u2014the fix only removes an incorrect assertion while leaving correct deactivate_locked behavior unchanged.\nA:H - WARN_ON_ONCE in softirq receive context can panic the kernel when panic_on_warn is set (and warn_limit exhaustion similarly), producing a denial of service inducible by an unauthenticated peer."
}
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}
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
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.
Vulnerability timeline
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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.
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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.