CVE-2025-37871
Estado: ModificadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
nfsd: decrease sc_count directly if fail to queue dl_recall
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.
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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.
Detalles técnicos trazas, registros y código del informe original
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_lockCVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.78%
- Percentil entre todas las CVEs puntuadas: 54
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (2)
CWE
- NVD-CWE-noinfo
Referencias
- https://git.kernel.org/stable/c/14985d66b9b99c12995dd99d1c6c8dec4114c2a5
- https://git.kernel.org/stable/c/7d192e27a431026c58d60edf66dc6cd98d0c01fc
- https://git.kernel.org/stable/c/a1d14d931bf700c1025db8c46d6731aa5cf440f9
- https://git.kernel.org/stable/c/a70832d3555987035fc430ccd703acd89393eadb
- https://git.kernel.org/stable/c/a7fce086f6ca84db409b9d58493ea77c1978897c
- https://git.kernel.org/stable/c/b9bbe8f9d5663311d06667ce36d6ed255ead1a26
- https://git.kernel.org/stable/c/ba903539fff745d592d893c71b30e5e268a95413
- https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
JSON original (NVD)
Mostrar
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"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->flc_lock\n spin_lock // clp->cl_lock\n nfs4_lockowner_has_blockers\n locks_owner_has_blockers\n spin_lock // flctx->flc_lock\n nfsd_break_deleg_cb\n nfsd_break_one_deleg\n nfs4_put_stid\n refcount_dec_and_lock\n spin_lock // clp->cl_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 --> destroy_delegation --> destroy_unhashed_deleg -->\nnfs4_unlock_deleg_lease --> kernel_setlease --> 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 después de una operación de cola dl_recall fallida: 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 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 delegación. El file_lease se asocia entonces con el archivo a través de kernel_setlease. La disociación se realiza en nfsd4_delegreturn mediante la siguiente cadena de llamadas: nfsd4_delegreturn --> destroy_delegation --> destroy_unhashed_deleg --> nfs4_unlock_deleg_lease --> kernel_setlease --> generic_delete_lease La referencia sc_count correspondiente se liberará después de esta disociación. Dado que nfsd_break_one_deleg se ejecuta mientras mantiene el flc_lock, el proceso de disociación se bloquea al intentar adquirir flc_lock en generic_delete_lease. Esto significa: 1) sc_count en nfsd_break_one_deleg no se decrementará a 0; 2) El `nfs4_put_stid` llamado por `nfsd_break_one_deleg` no intentará adquirir `cl_lock`; 3) Por consiguiente, no se crea ninguna condición 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 activación de advertencias de interbloqueo."
}
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"lastModified": "2026-07-30T06:22:24.690",
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