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CVE-2026-46290

Estado: AnalizadaMedia (5.5)—

In the Linux kernel, the following vulnerability has been resolved:

x86/efi: Fix graceful fault handling after FPU softirq changes

Since commit d02198550423 ("x86/fpu: Improve crypto performance by making kernel-mode FPU reliably usable in softirqs"), kernel_fpu_begin() calls fpregs_lock() which uses local_bh_disable() instead of the previous preempt_disable(). This sets SOFTIRQ_OFFSET in preempt_count during the entire EFI runtime service call, causing in_interrupt() to return true in normal task context.

The graceful page fault handler efi_crash_gracefully_on_page_fault() uses in_interrupt() to bail out for faults in real interrupt context.

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With SOFTIRQ_OFFSET now set, the handler always bails out, leaving EFI firmware page faults unhandled. This escalates to die() which also sees in_interrupt() as true and calls panic("Fatal exception in interrupt"), resulting in a hard system freeze. On systems with buggy firmware that triggers page faults during EFI runtime calls (e.g., accessing unmapped memory in GetTime()), this causes an unrecoverable hang instead of the expected graceful EFI_ABORTED recovery.

Fix by replacing in_interrupt() with !in_task(). This preserves the original intent of bailing for interrupts or NMI faults, while no longer falsely triggering from the FPU code path's local_bh_disable().

Detalles técnicos trazas, registros y código del informe original
[ardb: Sashiko spotted that using 'in_hardirq() || in_nmi()' leaves a
       window where a softirq may be taken before fpregs_lock() is
       called, but after efi_rts_work.efi_rts_id has been assigned,
       and any page faults occurring in that window will then be
       misidentified as having been caused by the firmware. Instead,
       use !in_task(), which incorporates in_serving_softirq(). ]

CVSS

Probabilidad de explotación (EPSS)

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)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-46290",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
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          "product": "Linux",
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          "programFiles": [
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          "defaultStatus": "affected"
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  "published": "2026-06-08T17:16:47.230",
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      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "nvd@nist.gov",
      "description": [
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          "lang": "en",
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  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/efi: Fix graceful fault handling after FPU softirq changes\n\nSince commit d02198550423 (\"x86/fpu: Improve crypto performance by\nmaking kernel-mode FPU reliably usable in softirqs\"), kernel_fpu_begin()\ncalls fpregs_lock() which uses local_bh_disable() instead of the\nprevious preempt_disable(). This sets SOFTIRQ_OFFSET in preempt_count\nduring the entire EFI runtime service call, causing in_interrupt() to\nreturn true in normal task context.\n\nThe graceful page fault handler efi_crash_gracefully_on_page_fault()\nuses in_interrupt() to bail out for faults in real interrupt context.\nWith SOFTIRQ_OFFSET now set, the handler always bails out, leaving EFI\nfirmware page faults unhandled. This escalates to die() which also sees\nin_interrupt() as true and calls panic(\"Fatal exception in interrupt\"),\nresulting in a hard system freeze. On systems with buggy firmware that\ntriggers page faults during EFI runtime calls (e.g., accessing unmapped\nmemory in GetTime()), this causes an unrecoverable hang instead of the\nexpected graceful EFI_ABORTED recovery.\n\nFix by replacing in_interrupt() with !in_task(). This preserves the\noriginal intent of bailing for interrupts or NMI faults, while no longer\nfalsely triggering from the FPU code path's local_bh_disable().\n\n[ardb: Sashiko spotted that using 'in_hardirq() || in_nmi()' leaves a\n       window where a softirq may be taken before fpregs_lock() is\n       called, but after efi_rts_work.efi_rts_id has been assigned,\n       and any page faults occurring in that window will then be\n       misidentified as having been caused by the firmware. Instead,\n       use !in_task(), which incorporates in_serving_softirq(). ]"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nx86/efi: Corrección del manejo elegante de fallos después de los cambios en softirq de FPU\n\nDesde el commit d02198550423 ('x86/fpu: Mejorar el rendimiento criptográfico haciendo que la FPU en modo kernel sea utilizable de forma fiable en softirqs'), kernel_fpu_begin() llama a fpregs_lock() que usa local_bh_disable() en lugar del preempt_disable() anterior. Esto establece SOFTIRQ_OFFSET en preempt_count durante toda la llamada al servicio de tiempo de ejecución de EFI, haciendo que in_interrupt() devuelva verdadero en un contexto de tarea normal.\n\nEl gestor elegante de fallos de página efi_crash_gracefully_on_page_fault() usa in_interrupt() para salir de los fallos en un contexto de interrupción real. Con SOFTIRQ_OFFSET ahora establecido, el gestor siempre sale, dejando los fallos de página del firmware EFI sin manejar. Esto escala a die() que también ve in_interrupt() como verdadero y llama a panic('Excepción fatal en interrupción'), resultando en una congelación dura del sistema. En sistemas con firmware defectuoso que dispara fallos de página durante las llamadas de tiempo de ejecución de EFI (p. ej., acceder a memoria no mapeada en GetTime()), esto causa un cuelgue irrecuperable en lugar de la recuperación elegante EFI_ABORTED esperada.\n\nSolución reemplazando in_interrupt() con !in_task(). Esto preserva la intención original de salir por interrupciones o fallos NMI, mientras ya no se dispara falsamente desde el local_bh_disable() de la ruta de código de la FPU.\n\n[ardb: Sashiko detectó que usar 'in_hardirq() || in_nmi()' deja una ventana donde un softirq puede ser tomado antes de que se llame a fpregs_lock(), pero después de que efi_rts_work.efi_rts_id haya sido asignado, y cualquier fallo de página que ocurra en esa ventana será entonces mal identificado como causado por el firmware. En su lugar, use !in_task(), que incorpora in_serving_softirq(). ]"
    }
  ],
  "lastModified": "2026-07-23T08:10:00.137",
  "configurations": [
    {
      "nodes": [
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