fkie_cve-2022-49171
Vulnerability from fkie_nvd
Published
2025-02-26 07:00
Modified
2025-02-26 07:00
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: don't BUG if someone dirty pages without asking ext4 first [un]pin_user_pages_remote is dirtying pages without properly warning the file system in advance. A related race was noted by Jan Kara in 2018[1]; however, more recently instead of it being a very hard-to-hit race, it could be reliably triggered by process_vm_writev(2) which was discovered by Syzbot[2]. This is technically a bug in mm/gup.c, but arguably ext4 is fragile in that if some other kernel subsystem dirty pages without properly notifying the file system using page_mkwrite(), ext4 will BUG, while other file systems will not BUG (although data will still be lost). So instead of crashing with a BUG, issue a warning (since there may be potential data loss) and just mark the page as clean to avoid unprivileged denial of service attacks until the problem can be properly fixed. More discussion and background can be found in the thread starting at [2]. [1] https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz [2] https://lore.kernel.org/r/Yg0m6IjcNmfaSokM@google.com
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0d3a6926f7e8be3c897fa46216ce13b119a9f56a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/330d0e44fc5a47c27df958ecdd4693a3cb1d8b81
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/343117559ef41e992e326f7a92da1a8f254dfa8c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5a016c053f426a73752c3b41b60b497b58694d48
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5db60e76edf5680ff1f3a7221036fc44b308f146
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/677c9d30e8487bee6c8e3b034070319d98f6e203
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a0856764dc1276ad2dc7891288c2e9246bf11a37
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cc5095747edfb054ca2068d01af20be3fcc3634f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d666dfaa571465a19f014534a214c255ea33f301
Impacted products
Vendor Product Version


To clipboard 

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: don\u0027t BUG if someone dirty pages without asking ext4 first\n\n[un]pin_user_pages_remote is dirtying pages without properly warning\nthe file system in advance.  A related race was noted by Jan Kara in\n2018[1]; however, more recently instead of it being a very hard-to-hit\nrace, it could be reliably triggered by process_vm_writev(2) which was\ndiscovered by Syzbot[2].\n\nThis is technically a bug in mm/gup.c, but arguably ext4 is fragile in\nthat if some other kernel subsystem dirty pages without properly\nnotifying the file system using page_mkwrite(), ext4 will BUG, while\nother file systems will not BUG (although data will still be lost).\n\nSo instead of crashing with a BUG, issue a warning (since there may be\npotential data loss) and just mark the page as clean to avoid\nunprivileged denial of service attacks until the problem can be\nproperly fixed.  More discussion and background can be found in the\nthread starting at [2].\n\n[1] https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz\n[2] https://lore.kernel.org/r/Yg0m6IjcNmfaSokM@google.com"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: no generar ERRORES si alguien ensucia p\u00e1ginas sin preguntar primero a ext4 [un]pin_user_pages_remote est\u00e1 ensuciando p\u00e1ginas sin advertir adecuadamente al sistema de archivos con anticipaci\u00f3n. Jan Kara not\u00f3 una ejecuci\u00f3n relacionada en 2018[1]; sin embargo, m\u00e1s recientemente, en lugar de ser una ejecuci\u00f3n muy dif\u00edcil de alcanzar, podr\u00eda ser activada de manera confiable por process_vm_writev(2) que fue descubierto por Syzbot[2]. T\u00e9cnicamente, esto es un error en mm/gup.c, pero podr\u00eda decirse que ext4 es fr\u00e1gil en el sentido de que si alg\u00fan otro subsistema del kernel ensucia p\u00e1ginas sin notificar adecuadamente al sistema de archivos usando page_mkwrite(), ext4 generar\u00e1 ERRORES, mientras que otros sistemas de archivos no generar\u00e1n ERRORES (aunque a\u00fan se perder\u00e1n datos). Entonces, en lugar de bloquearse con un ERROR, emita una advertencia (ya que puede haber una posible p\u00e9rdida de datos) y simplemente marque la p\u00e1gina como limpia para evitar ataques de denegaci\u00f3n de servicio sin privilegios hasta que el problema pueda solucionarse correctamente. Se puede encontrar m\u00e1s discusi\u00f3n y antecedentes en el hilo que comienza en [2]. [1] https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz [2] https://lore.kernel.org/r/Yg0m6IjcNmfaSokM@google.com"
    }
  ],
  "id": "CVE-2022-49171",
  "lastModified": "2025-02-26T07:00:54.213",
  "metrics": {},
  "published": "2025-02-26T07:00:54.213",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0d3a6926f7e8be3c897fa46216ce13b119a9f56a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/330d0e44fc5a47c27df958ecdd4693a3cb1d8b81"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/343117559ef41e992e326f7a92da1a8f254dfa8c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5a016c053f426a73752c3b41b60b497b58694d48"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5db60e76edf5680ff1f3a7221036fc44b308f146"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/677c9d30e8487bee6c8e3b034070319d98f6e203"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a0856764dc1276ad2dc7891288c2e9246bf11a37"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/cc5095747edfb054ca2068d01af20be3fcc3634f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d666dfaa571465a19f014534a214c255ea33f301"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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