CVE-2025-21876
Estado: ModificadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
iommu/vt-d: Fix suspicious RCU usage
Commit <d74169ceb0d2> ("iommu/vt-d: Allocate DMAR fault interrupts locally") moved the call to enable_drhd_fault_handling() to a code path that does not hold any lock while traversing the drhd list. Fix it by ensuring the dmar_global_lock lock is held when traversing the drhd list.
Holding the lock in enable_drhd_fault_handling() triggers a lockdep splat about a possible deadlock between dmar_global_lock and cpu_hotplug_lock. This is avoided by not holding dmar_global_lock when calling iommu_device_register(), which initiates the device probe process.
Detalles técnicos trazas, registros y código del informe original
Without this fix, the following warning is triggered:
=============================
WARNING: suspicious RCU usage
6.14.0-rc3 #55 Not tainted
-----------------------------
drivers/iommu/intel/dmar.c:2046 RCU-list traversed in non-reader section!!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 1
2 locks held by cpuhp/1/23:
#0: ffffffff84a67c50 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0
#1: ffffffff84a6a380 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0
stack backtrace:
CPU: 1 UID: 0 PID: 23 Comm: cpuhp/1 Not tainted 6.14.0-rc3 #55
Call Trace:
<TASK>
dump_stack_lvl+0xb7/0xd0
lockdep_rcu_suspicious+0x159/0x1f0
? __pfx_enable_drhd_fault_handling+0x10/0x10
enable_drhd_fault_handling+0x151/0x180
cpuhp_invoke_callback+0x1df/0x990
cpuhp_thread_fun+0x1ea/0x2c0
smpboot_thread_fn+0x1f5/0x2e0
? __pfx_smpboot_thread_fn+0x10/0x10
kthread+0x12a/0x2d0
? __pfx_kthread+0x10/0x10
ret_from_fork+0x4a/0x60
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>CVSS
- 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: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- 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 (1)
CWE
- NVD-CWE-noinfo
Referencias
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Fix suspicious RCU usage\n\nCommit <d74169ceb0d2> (\"iommu/vt-d: Allocate DMAR fault interrupts\nlocally\") moved the call to enable_drhd_fault_handling() to a code\npath that does not hold any lock while traversing the drhd list. Fix\nit by ensuring the dmar_global_lock lock is held when traversing the\ndrhd list.\n\nWithout this fix, the following warning is triggered:\n =============================\n WARNING: suspicious RCU usage\n 6.14.0-rc3 #55 Not tainted\n -----------------------------\n drivers/iommu/intel/dmar.c:2046 RCU-list traversed in non-reader section!!\n other info that might help us debug this:\n rcu_scheduler_active = 1, debug_locks = 1\n 2 locks held by cpuhp/1/23:\n #0: ffffffff84a67c50 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0\n #1: ffffffff84a6a380 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0\n stack backtrace:\n CPU: 1 UID: 0 PID: 23 Comm: cpuhp/1 Not tainted 6.14.0-rc3 #55\n Call Trace:\n <TASK>\n dump_stack_lvl+0xb7/0xd0\n lockdep_rcu_suspicious+0x159/0x1f0\n ? __pfx_enable_drhd_fault_handling+0x10/0x10\n enable_drhd_fault_handling+0x151/0x180\n cpuhp_invoke_callback+0x1df/0x990\n cpuhp_thread_fun+0x1ea/0x2c0\n smpboot_thread_fn+0x1f5/0x2e0\n ? __pfx_smpboot_thread_fn+0x10/0x10\n kthread+0x12a/0x2d0\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x4a/0x60\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1a/0x30\n </TASK>\n\nHolding the lock in enable_drhd_fault_handling() triggers a lockdep splat\nabout a possible deadlock between dmar_global_lock and cpu_hotplug_lock.\nThis is avoided by not holding dmar_global_lock when calling\niommu_device_register(), which initiates the device probe process."
},
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"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: iommu/vt-d: Corrección de uso sospechoso de RCU. El commit (\"iommu/vt-d: Asignar interrupciones de fallo DMAR localmente\") movió la llamada a enable_drhd_fault_handling() a una ruta de código que no mantiene ningún bloqueo al recorrer la lista drhd. Corríjala asegurándose de que el bloqueo dmar_global_lock se mantenga al recorrer la lista drhd. Sin esta corrección, se activa la siguiente advertencia: ============================= ADVERTENCIA: uso sospechoso de RCU 6.14.0-rc3 #55 No contaminado ----------------------------- drivers/iommu/intel/dmar.c:2046 ¡Lista de RCU recorrida en una sección que no es de lectura! Otra información que podría ayudarnos a depurar esto: rcu_scheduler_active = 1, debug_locks = 1 2 bloqueos mantenidos por cpuhp/1/23: #0: ffffffff84a67c50 (cpu_hotplug_lock){++++}-{0:0}, en: cpuhp_thread_fun+0x87/0x2c0 #1: ffffffff84a6a380 (cpuhp_state-up){+.+.}-{0:0}, en: cpuhp_thread_fun+0x87/0x2c0 seguimiento de pila: CPU: 1 UID: 0 PID: 23 Comm: cpuhp/1 No contaminado 6.14.0-rc3 #55 Seguimiento de llamadas: dump_stack_lvl+0xb7/0xd0 lockdep_rcu_suspicious+0x159/0x1f0 ? __pfx_enable_drhd_fault_handling+0x10/0x10 enable_drhd_fault_handling+0x151/0x180 cpuhp_invoke_callback+0x1df/0x990 cpuhp_thread_fun+0x1ea/0x2c0 smpboot_thread_fn+0x1f5/0x2e0 ? __pfx_smpboot_thread_fn+0x10/0x10 kthread+0x12a/0x2d0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x4a/0x60 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 Mantener el bloqueo en enable_drhd_fault_handling() activa un aviso de bloqueo sobre un posible interbloqueo entre dmar_global_lock y cpu_hotplug_lock. Esto se evita al no mantener dmar_global_lock al llamar a iommu_device_register(), que inicia el proceso de sondeo del dispositivo."
}
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"lastModified": "2026-07-30T06:21:42.660",
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