CVE-2021-4454 (GCVE-0-2021-4454)

Vulnerability from cvelistv5 – Published: 2025-03-27 16:37 – Updated: 2026-10-15 21:21
VLAI
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)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-15 21:02 UTC
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6640 records in the last 180 days details
References
Impacted 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 Create a notification for this product.
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)
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        "cveTags": [],
        "descriptions": [
          {
            "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"
          },
          {
            "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 "
          }
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        "id": "CVE-2021-4454",
        "lastModified": "2026-10-15T22:17:22.303",
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      "product_status:known_affected": "108",
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      "source": "Red Hat CSAF VEX",
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      "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",
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      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2025/cve-2021-4454.json",
      "version": "42"
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    "vulnrichment": {
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              "shortName": "CISA-ADP"
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        "cna": {
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              "product": "Linux",
              "programFiles": [
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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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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                  "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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            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "dateReserved": "2025-02-26T02:29:43.631Z",
        "dateUpdated": "2026-10-15T21:21:06.266Z",
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  }
}



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