CVE-2021-47228

x86/ioremap: Map EFI-reserved memory as encrypted for SEV

Severity Score

"-"

*CVSS v-

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Track

*SSVC

Descriptions

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

x86/ioremap: Map EFI-reserved memory as encrypted for SEV

Some drivers require memory that is marked as EFI boot services
data. In order for this memory to not be re-used by the kernel
after ExitBootServices(), efi_mem_reserve() is used to preserve it
by inserting a new EFI memory descriptor and marking it with the
EFI_MEMORY_RUNTIME attribute.

Under SEV, memory marked with the EFI_MEMORY_RUNTIME attribute needs to
be mapped encrypted by Linux, otherwise the kernel might crash at boot
like below:

EFI Variables Facility v0.08 2004-May-17
general protection fault, probably for non-canonical address 0x3597688770a868b2: 0000 [#1] SMP NOPTI
CPU: 13 PID: 1 Comm: swapper/0 Not tainted 5.12.4-2-default #1 openSUSE Tumbleweed
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:efi_mokvar_entry_next
[...]
Call Trace:
efi_mokvar_sysfs_init
? efi_mokvar_table_init
do_one_initcall
? __kmalloc
kernel_init_freeable
? rest_init
kernel_init
ret_from_fork

Expand the __ioremap_check_other() function to additionally check for
this other type of boot data reserved at runtime and indicate that it
should be mapped encrypted for an SEV guest.

[ bp: Massage commit message. ]

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: x86/ioremap: asigne la memoria reservada de EFI como cifrada para SEV. Algunos controladores requieren memoria marcada como datos de servicios de arranque de EFI. Para que el kernel no reutilice esta memoria después de ExitBootServices(), se utiliza efi_mem_reserve() para preservarla insertando un nuevo descriptor de memoria EFI y marcándolo con el atributo EFI_MEMORY_RUNTIME. En SEV, la memoria marcada con el atributo EFI_MEMORY_RUNTIME debe ser asignada cifrada por Linux; de lo contrario, el kernel podría fallar en el arranque como se muestra a continuación: EFI Variables Facility v0.08 2004-May-17 falla de protección general, probablemente para la dirección no canónica 0x3597688770a868b2: 0000 [#1] SMP NOPTI CPU: 13 PID: 1 Comm: swapper/0 No contaminado 5.12.4-2-default #1 openSUSE Tumbleweed Nombre del hardware: PC estándar QEMU (Q35 + ICH9, 2009), BIOS 0.0.0 02 /06/2015 RIP: 0010:efi_mokvar_entry_next [...] Seguimiento de llamadas: efi_mokvar_sysfs_init? efi_mokvar_table_init do_one_initcall? __kmalloc kernel_init_freeable? rest_init kernel_init ret_from_fork Expanda la función __ioremap_check_other() para verificar adicionalmente este otro tipo de datos de arranque reservados en tiempo de ejecución e indicar que deben asignarse cifrados para un invitado SEV. [pb: mensaje de confirmación de masaje. ]

*Credits: N/A

CVSS Scores

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Scope

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Integrity

Availability

* Common Vulnerability Scoring System

SSVC

Decision:Track

Exploitation

None

Automatable

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2024-04-10 CVE Reserved
2024-05-21 CVE Published
2024-05-22 EPSS Updated
2024-08-04 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (4)

URL	Tag	Source
https://git.kernel.org/stable/c/58c909022a5a56cd1d9e89c8c5461fd1f6a27bb5	Vuln. Introduced

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/208bb686e7fa7fff16e8fa78ff0db34aa9acdbd7	2021-06-23
https://git.kernel.org/stable/c/b7a05aba39f733ec337c5b952e112dd2dc4fc404	2021-06-23
https://git.kernel.org/stable/c/8d651ee9c71bb12fc0c8eb2786b66cbe5aa3e43b	2021-06-08

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.10 < 5.10.46 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10 < 5.10.46"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.10 < 5.12.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10 < 5.12.13"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.10 < 5.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10 < 5.13"		en		Affected