fkie_cve-2025-37871
Vulnerability from fkie_nvd
Published
2025-05-09 07:16
Modified
2025-05-12 17:32
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: decrease sc_count directly if fail to queue dl_recall A deadlock warning occurred when invoking nfs4_put_stid following a failed dl_recall queue operation: T1 T2 nfs4_laundromat nfs4_get_client_reaplist nfs4_anylock_blockers __break_lease spin_lock // ctx->flc_lock spin_lock // clp->cl_lock nfs4_lockowner_has_blockers locks_owner_has_blockers spin_lock // flctx->flc_lock nfsd_break_deleg_cb nfsd_break_one_deleg nfs4_put_stid refcount_dec_and_lock spin_lock // clp->cl_lock When a file is opened, an nfs4_delegation is allocated with sc_count initialized to 1, and the file_lease holds a reference to the delegation. The file_lease is then associated with the file through kernel_setlease. The disassociation is performed in nfsd4_delegreturn via the following call chain: nfsd4_delegreturn --> destroy_delegation --> destroy_unhashed_deleg --> nfs4_unlock_deleg_lease --> kernel_setlease --> generic_delete_lease The corresponding sc_count reference will be released after this disassociation. Since nfsd_break_one_deleg executes while holding the flc_lock, the disassociation process becomes blocked when attempting to acquire flc_lock in generic_delete_lease. This means: 1) sc_count in nfsd_break_one_deleg will not be decremented to 0; 2) The nfs4_put_stid called by nfsd_break_one_deleg will not attempt to acquire cl_lock; 3) Consequently, no deadlock condition is created. Given that sc_count in nfsd_break_one_deleg remains non-zero, we can safely perform refcount_dec on sc_count directly. This approach effectively avoids triggering deadlock warnings.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/14985d66b9b99c12995dd99d1c6c8dec4114c2a5
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7d192e27a431026c58d60edf66dc6cd98d0c01fc
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a1d14d931bf700c1025db8c46d6731aa5cf440f9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a70832d3555987035fc430ccd703acd89393eadb
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a7fce086f6ca84db409b9d58493ea77c1978897c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b9bbe8f9d5663311d06667ce36d6ed255ead1a26
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ba903539fff745d592d893c71b30e5e268a95413
Impacted products
Vendor Product Version


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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: decrease sc_count directly if fail to queue dl_recall\n\nA deadlock warning occurred when invoking nfs4_put_stid following a failed\ndl_recall queue operation:\n            T1                            T2\n                                nfs4_laundromat\n                                 nfs4_get_client_reaplist\n                                  nfs4_anylock_blockers\n__break_lease\n spin_lock // ctx-\u003eflc_lock\n                                   spin_lock // clp-\u003ecl_lock\n                                   nfs4_lockowner_has_blockers\n                                    locks_owner_has_blockers\n                                     spin_lock // flctx-\u003eflc_lock\n nfsd_break_deleg_cb\n  nfsd_break_one_deleg\n   nfs4_put_stid\n    refcount_dec_and_lock\n     spin_lock // clp-\u003ecl_lock\n\nWhen a file is opened, an nfs4_delegation is allocated with sc_count\ninitialized to 1, and the file_lease holds a reference to the delegation.\nThe file_lease is then associated with the file through kernel_setlease.\n\nThe disassociation is performed in nfsd4_delegreturn via the following\ncall chain:\nnfsd4_delegreturn --\u003e destroy_delegation --\u003e destroy_unhashed_deleg --\u003e\nnfs4_unlock_deleg_lease --\u003e kernel_setlease --\u003e generic_delete_lease\nThe corresponding sc_count reference will be released after this\ndisassociation.\n\nSince nfsd_break_one_deleg executes while holding the flc_lock, the\ndisassociation process becomes blocked when attempting to acquire flc_lock\nin generic_delete_lease. This means:\n1) sc_count in nfsd_break_one_deleg will not be decremented to 0;\n2) The nfs4_put_stid called by nfsd_break_one_deleg will not attempt to\nacquire cl_lock;\n3) Consequently, no deadlock condition is created.\n\nGiven that sc_count in nfsd_break_one_deleg remains non-zero, we can\nsafely perform refcount_dec on sc_count directly. This approach\neffectively avoids triggering deadlock warnings."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: nfsd: disminuir sc_count directamente si no se puede poner en cola dl_recall Se produjo una advertencia de bloqueo al invocar nfs4_put_stid despu\u00e9s de una operaci\u00f3n de cola dl_recall fallida: T1 T2 nfs4_laundromat nfs4_get_client_reaplist nfs4_anylock_blockers __break_lease spin_lock // ctx-\u0026gt;flc_lock spin_lock // clp-\u0026gt;cl_lock nfs4_lockowner_has_blockers locks_owner_has_blockers spin_lock // flctx-\u0026gt;flc_lock nfsd_break_deleg_cb nfsd_break_one_deleg nfs4_put_stid refcount_dec_and_lock spin_lock // clp-\u0026gt;cl_lock Cuando se abre un archivo, se genera una nfs4_delegation asignado con sc_count inicializado a 1, y el file_lease contiene una referencia a la delegaci\u00f3n. El file_lease se asocia entonces con el archivo a trav\u00e9s de kernel_setlease. La disociaci\u00f3n se realiza en nfsd4_delegreturn mediante la siguiente cadena de llamadas: nfsd4_delegreturn --\u0026gt; destroy_delegation --\u0026gt; destroy_unhashed_deleg --\u0026gt; nfs4_unlock_deleg_lease --\u0026gt; kernel_setlease --\u0026gt; generic_delete_lease La referencia sc_count correspondiente se liberar\u00e1 despu\u00e9s de esta disociaci\u00f3n. Dado que nfsd_break_one_deleg se ejecuta mientras mantiene el flc_lock, el proceso de disociaci\u00f3n se bloquea al intentar adquirir flc_lock en generic_delete_lease. Esto significa: 1) sc_count en nfsd_break_one_deleg no se decrementar\u00e1 a 0; 2) El `nfs4_put_stid` llamado por `nfsd_break_one_deleg` no intentar\u00e1 adquirir `cl_lock`; 3) Por consiguiente, no se crea ninguna condici\u00f3n de interbloqueo. Dado que `sc_count` en `nfsd_break_one_deleg` permanece distinto de cero, podemos ejecutar `refcount_dec` en `sc_count` directamente. Este enfoque evita eficazmente la activaci\u00f3n de advertencias de interbloqueo."
    }
  ],
  "id": "CVE-2025-37871",
  "lastModified": "2025-05-12T17:32:32.760",
  "metrics": {},
  "published": "2025-05-09T07:16:08.210",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/14985d66b9b99c12995dd99d1c6c8dec4114c2a5"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7d192e27a431026c58d60edf66dc6cd98d0c01fc"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a1d14d931bf700c1025db8c46d6731aa5cf440f9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a70832d3555987035fc430ccd703acd89393eadb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a7fce086f6ca84db409b9d58493ea77c1978897c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b9bbe8f9d5663311d06667ce36d6ed255ead1a26"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ba903539fff745d592d893c71b30e5e268a95413"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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