CVE-2025-21876

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. 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> 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.
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:*

History

30 Oct 2025, 16:00

Type Values Removed Values Added
Summary
  • (es) 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.
References () https://git.kernel.org/stable/c/4117c72938493a77ab53cc4b8284be8fb6ec8065 - () https://git.kernel.org/stable/c/4117c72938493a77ab53cc4b8284be8fb6ec8065 - Patch
References () https://git.kernel.org/stable/c/b150654f74bf0df8e6a7936d5ec51400d9ec06d8 - () https://git.kernel.org/stable/c/b150654f74bf0df8e6a7936d5ec51400d9ec06d8 - Patch
References () https://git.kernel.org/stable/c/c603ccbe91d189849e1439134598ec567088dcec - () https://git.kernel.org/stable/c/c603ccbe91d189849e1439134598ec567088dcec - Patch
CVSS v2 : unknown
v3 : unknown
v2 : unknown
v3 : 5.5
CWE NVD-CWE-noinfo
First Time Linux linux Kernel
Linux
CPE cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

27 Mar 2025, 15:15

Type Values Removed Values Added
New CVE

Information

Published : 2025-03-27 15:15

Updated : 2025-10-30 16:00


NVD link : CVE-2025-21876

Mitre link : CVE-2025-21876

CVE.ORG link : CVE-2025-21876


JSON object : View

Products Affected

linux

  • linux_kernel