CVE-2021-47008

2024-02-2809:15:38

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

web.nvd.nist.gov

696

cve-2021-47008

linux kernel

vulnerability

kvm

ghcb

svm

null pointer dereference

nvd

6.4 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

15.7%

JSON

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

KVM: SVM: Make sure GHCB is mapped before updating

Access to the GHCB is mainly in the VMGEXIT path and it is known that the
GHCB will be mapped. But there are two paths where it is possible the GHCB
might not be mapped.

The sev_vcpu_deliver_sipi_vector() routine will update the GHCB to inform
the caller of the AP Reset Hold NAE event that a SIPI has been delivered.
However, if a SIPI is performed without a corresponding AP Reset Hold,
then the GHCB might not be mapped (depending on the previous VMEXIT),
which will result in a NULL pointer dereference.

The svm_complete_emulated_msr() routine will update the GHCB to inform
the caller of a RDMSR/WRMSR operation about any errors. While it is likely
that the GHCB will be mapped in this situation, add a safe guard
in this path to be certain a NULL pointer dereference is not encountered.

Affected configurations

Vulners

Node

linuxlinux_kernelRange5.11–5.11.22

linuxlinux_kernelRange5.12.0–5.12.5

linuxlinux_kernelRange5.13.0≥

VendorProductVersionCPE
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

Vendor	Product	Version	CPE
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/x86/kvm/svm/sev.c",
      "arch/x86/kvm/svm/svm.c"
    ],
    "versions": [
      {
        "version": "647daca25d24",
        "lessThan": "fb9e14f4f821",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "647daca25d24",
        "lessThan": "fd722a57fe0b",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "647daca25d24",
        "lessThan": "a3ba26ecfb56",
        "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/kvm/svm/sev.c",
      "arch/x86/kvm/svm/svm.c"
    ],
    "versions": [
      {
        "version": "5.11",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.11",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.11.22",
        "lessThanOrEqual": "5.11.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.12.5",
        "lessThanOrEqual": "5.12.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.13",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]