fkie_cve-2022-49886
Vulnerability from fkie_nvd
Published
2025-05-01 15:16
Modified
2025-05-02 13:52
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
x86/tdx: Panic on bad configs that #VE on "private" memory access
All normal kernel memory is "TDX private memory". This includes
everything from kernel stacks to kernel text. Handling
exceptions on arbitrary accesses to kernel memory is essentially
impossible because they can happen in horribly nasty places like
kernel entry/exit. But, TDX hardware can theoretically _deliver_
a virtualization exception (#VE) on any access to private memory.
But, it's not as bad as it sounds. TDX can be configured to never
deliver these exceptions on private memory with a "TD attribute"
called ATTR_SEPT_VE_DISABLE. The guest has no way to *set* this
attribute, but it can check it.
Ensure ATTR_SEPT_VE_DISABLE is set in early boot. panic() if it
is unset. There is no sane way for Linux to run with this
attribute clear so a panic() is appropriate.
There's small window during boot before the check where kernel
has an early #VE handler. But the handler is only for port I/O
and will also panic() as soon as it sees any other #VE, such as
a one generated by a private memory access.
[ dhansen: Rewrite changelog and rebase on new tdx_parse_tdinfo().
Add Kirill's tested-by because I made changes since
he wrote this. ]
References
Impacted products
| Vendor | Product | Version |
|---|
{
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/tdx: Panic on bad configs that #VE on \"private\" memory access\n\nAll normal kernel memory is \"TDX private memory\". This includes\neverything from kernel stacks to kernel text. Handling\nexceptions on arbitrary accesses to kernel memory is essentially\nimpossible because they can happen in horribly nasty places like\nkernel entry/exit. But, TDX hardware can theoretically _deliver_\na virtualization exception (#VE) on any access to private memory.\n\nBut, it\u0027s not as bad as it sounds. TDX can be configured to never\ndeliver these exceptions on private memory with a \"TD attribute\"\ncalled ATTR_SEPT_VE_DISABLE. The guest has no way to *set* this\nattribute, but it can check it.\n\nEnsure ATTR_SEPT_VE_DISABLE is set in early boot. panic() if it\nis unset. There is no sane way for Linux to run with this\nattribute clear so a panic() is appropriate.\n\nThere\u0027s small window during boot before the check where kernel\nhas an early #VE handler. But the handler is only for port I/O\nand will also panic() as soon as it sees any other #VE, such as\na one generated by a private memory access.\n\n[ dhansen: Rewrite changelog and rebase on new tdx_parse_tdinfo().\n\t Add Kirill\u0027s tested-by because I made changes since\n\t he wrote this. ]"
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: x86/tdx: P\u00e1nico en configuraciones incorrectas que generan #VE al acceder a memoria \"privada\". Toda la memoria normal del kernel es \"memoria privada TDX\". Esto incluye todo, desde las pilas del kernel hasta el texto del kernel. Gestionar excepciones en accesos arbitrarios a la memoria del kernel es pr\u00e1cticamente imposible, ya que pueden ocurrir en lugares muy peligrosos, como la entrada/salida del kernel. Sin embargo, el hardware TDX, en teor\u00eda, puede generar una excepci\u00f3n de virtualizaci\u00f3n (#VE) en cualquier acceso a memoria privada. Sin embargo, no es tan grave como parece. TDX se puede configurar para que nunca genere estas excepciones en memoria privada con un \"atributo TD\" llamado ATTR_SEPT_VE_DISABLE. El invitado no tiene forma de *configurar* este atributo, pero puede comprobarlo. Aseg\u00farese de que ATTR_SEPT_VE_DISABLE est\u00e9 configurado en el arranque inicial. Si no est\u00e1 configurado, utilice panic(). No hay una forma sensata de que Linux se ejecute con este atributo sin configurar, por lo que es apropiado usar panic(). Hay una peque\u00f1a ventana durante el arranque antes de la comprobaci\u00f3n donde el kernel tiene un controlador de #VE temprano. Sin embargo, este controlador solo sirve para la E/S de puerto y tambi\u00e9n se pondr\u00e1 en p\u00e1nico() en cuanto detecte cualquier otro #VE, como uno generado por un acceso a memoria privada. [dhansen: Reescribir el registro de cambios y reorganizar con el nuevo tdx_parse_tdinfo(). A\u00f1adir la prueba de Kirill porque hice cambios desde que escribi\u00f3 esto.]"
}
],
"id": "CVE-2022-49886",
"lastModified": "2025-05-02T13:52:51.693",
"metrics": {},
"published": "2025-05-01T15:16:13.590",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/373e715e31bf4e0f129befe87613a278fac228d3"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/895c168c8f78079f21ad50fead7593ffa352f795"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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