CVE-2021-47459 (GCVE-0-2021-47459)

Vulnerability from cvelistv5 – Published: 2024-05-22 06:23 – Updated: 2026-08-05 08:47
VLAI
Title
can: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv
Summary
In the Linux kernel, the following vulnerability has been resolved: can: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv It will trigger UAF for rx_kref of j1939_priv as following. cpu0 cpu1 j1939_sk_bind(socket0, ndev0, ...) j1939_netdev_start j1939_sk_bind(socket1, ndev0, ...) j1939_netdev_start j1939_priv_set j1939_priv_get_by_ndev_locked j1939_jsk_add ..... j1939_netdev_stop kref_put_lock(&priv->rx_kref, ...) kref_get(&priv->rx_kref, ...) REFCOUNT_WARN("addition on 0;...") ==================================================== refcount_t: addition on 0; use-after-free. WARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 RIP: 0010:refcount_warn_saturate+0x169/0x1e0 Call Trace: j1939_netdev_start+0x68b/0x920 j1939_sk_bind+0x426/0xeb0 ? security_socket_bind+0x83/0xb0 The rx_kref's kref_get() and kref_put() should use j1939_netdev_lock to protect.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-09-10 15:36 UTC
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 9d71dd0c70099914fcd063135da3c580865e924c , < a0e47d2833b4f65e6c799f28c6b636d36b8b936d (git)
Affected: 9d71dd0c70099914fcd063135da3c580865e924c , < 864e77771a24c877aaf53aee019f78619cbcd668 (git)
Affected: 9d71dd0c70099914fcd063135da3c580865e924c , < 6e8811707e2df0c6ba920f0cad3a3bca7b42132f (git)
Affected: 9d71dd0c70099914fcd063135da3c580865e924c , < d9d52a3ebd284882f5562c88e55991add5d01586 (git)
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Linux Linux Affected: 5.4
Unaffected: 0 , < 5.4 (semver)
Unaffected: 5.4.156 , ≤ 5.4.* (semver)
Unaffected: 5.10.76 , ≤ 5.10.* (semver)
Unaffected: 5.14.15 , ≤ 5.14.* (semver)
Unaffected: 5.15 , ≤ * (original_commit_for_fix)
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv\n\nIt will trigger UAF for rx_kref of j1939_priv as following.\n\n        cpu0                                    cpu1\nj1939_sk_bind(socket0, ndev0, ...)\nj1939_netdev_start\n                                        j1939_sk_bind(socket1, ndev0, ...)\n                                        j1939_netdev_start\nj1939_priv_set\n                                        j1939_priv_get_by_ndev_locked\nj1939_jsk_add\n.....\nj1939_netdev_stop\nkref_put_lock(\u0026priv-\u003erx_kref, ...)\n                                        kref_get(\u0026priv-\u003erx_kref, ...)\n                                        REFCOUNT_WARN(\"addition on 0;...\")\n\n====================================================\nrefcount_t: addition on 0; use-after-free.\nWARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0\nRIP: 0010:refcount_warn_saturate+0x169/0x1e0\nCall Trace:\n j1939_netdev_start+0x68b/0x920\n j1939_sk_bind+0x426/0xeb0\n ? security_socket_bind+0x83/0xb0\n\nThe rx_kref\u0027s kref_get() and kref_put() should use j1939_netdev_lock to\nprotect."
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: can: j1939: j1939_netdev_start(): arreglar UAF para rx_kref de j1939_priv Activar\u00e1 UAF para rx_kref de j1939_priv de la siguiente manera. cpu0 cpu1 j1939_sk_bind(socket0, ndev0, ...) j1939_netdev_start j1939_sk_bind(socket1, ndev0, ...) j1939_netdev_start j1939_priv_set j1939_priv_get_by_ndev_locked j1939_jsk_add ..... kref_put_lock(\u0026amp;priv-\u0026gt;rx_kref, ...) kref_get(\u0026amp;priv-\u0026gt;rx_kref , ...) REFCOUNT_WARN(\"adici\u00f3n en 0;...\") ================================== ==================== refcount_t: suma en 0; use-after-free. ADVERTENCIA: CPU: 1 PID: 20874 en lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 RIP: 0010:refcount_warn_saturate+0x169/0x1e0 Seguimiento de llamadas: j1939_netdev_start+0x68b/0x920 j1939_sk_bind+0x426 /0xeb0 ? security_socket_bind+0x83/0xb0 Los kref_get() y kref_put() de rx_kref deben usar j1939_netdev_lock para proteger."
          }
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        "id": "CVE-2021-47459",
        "lastModified": "2026-08-04T10:17:04.430",
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      "initial_release_date": "2021-01-01T00:00:00+00:00",
      "product_status:fixed": "513",
      "product_status:known_affected": "22",
      "product_status:known_not_affected": "91",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: can: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-47459.json",
      "version": "3"
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      "initial_release_date": "2024-05-25T03:33:58Z",
      "product_status:known_affected": "275",
      "product_status:known_not_affected": "266",
      "product_status:recommended": "481",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2021-47459",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2021-47459.json",
      "version": "56"
    },
    "vulnrichment": {
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              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv\n\nIt will trigger UAF for rx_kref of j1939_priv as following.\n\n        cpu0                                    cpu1\nj1939_sk_bind(socket0, ndev0, ...)\nj1939_netdev_start\n                                        j1939_sk_bind(socket1, ndev0, ...)\n                                        j1939_netdev_start\nj1939_priv_set\n                                        j1939_priv_get_by_ndev_locked\nj1939_jsk_add\n.....\nj1939_netdev_stop\nkref_put_lock(\u0026priv-\u003erx_kref, ...)\n                                        kref_get(\u0026priv-\u003erx_kref, ...)\n                                        REFCOUNT_WARN(\"addition on 0;...\")\n\n====================================================\nrefcount_t: addition on 0; use-after-free.\nWARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0\nRIP: 0010:refcount_warn_saturate+0x169/0x1e0\nCall Trace:\n j1939_netdev_start+0x68b/0x920\n j1939_sk_bind+0x426/0xeb0\n ? security_socket_bind+0x83/0xb0\n\nThe rx_kref\u0027s kref_get() and kref_put() should use j1939_netdev_lock to\nprotect."
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                  "value": "AV:L - The bug is reached only through local syscalls (socket/bind/close) into j1939_sk_bind \u2192 j1939_netdev_start/stop; it is not triggered by receiving CAN/J1939 frames from the wire.\nAC:L - The race is fully attacker-controlled by opening multiple J1939 sockets and concurrently binding/closing them on the same CAN interface, as demonstrated by the syzbot threaded reproducers.\nPR:L - Creating and binding CAN_J1939 sockets requires no capabilities; an unprivileged user can reach the path on an existing UP CAN device or by creating vcan in a user/net namespace with namespaced CAP_NET_ADMIN.\nUI:N - Exploitation requires no victim action beyond the attacker\u2019s own socket operations.\nS:U - This is a standard in-kernel memory-safety flaw affecting the host kernel authority, with no VM/IOMMU/sandbox boundary crossing.\nC:H - The vulnerability is a use-after-free on j1939_priv refcounting; UAF enables reclaim/spray of the freed object and arbitrary kernel memory disclosure.\nI:H - Use-after-free of j1939_priv state enables heap manipulation and write primitives sufficient for control-flow hijacking or arbitrary kernel writes.\nA:H - The UAF reliably produces refcount warnings and kernel oops/crash conditions even without full exploitation, denying availability."
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}



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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

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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.
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  • 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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