CVE-2021-47228

2024-05-2115:15:12

416baaa9-dc9f-4396-8d5f-8c081fb06d67

web.nvd.nist.gov

linux kernel

vulnerability

cve-2021-47228

x86/ioremap

efi-reserved memory

encrypted

sev

kernel crash

boot

efi_memory_runtime attribute

memory map

opensuse tumbleweed

6.4 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

15.5%

JSON

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. ]

Affected configurations

Vulners

Node

linuxlinux_kernelRange5.10–5.10.46

linuxlinux_kernelRange5.11.0–5.12.13

linuxlinux_kernelRange5.13.0≥

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/x86/mm/ioremap.c"
    ],
    "versions": [
      {
        "version": "58c909022a5a",
        "lessThan": "208bb686e7fa",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "58c909022a5a",
        "lessThan": "b7a05aba39f7",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "58c909022a5a",
        "lessThan": "8d651ee9c71b",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/x86/mm/ioremap.c"
    ],
    "versions": [
      {
        "version": "5.10",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.10",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.46",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.12.13",
        "lessThanOrEqual": "5.12.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.13",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]