CVE-2023-53647
Description
A NULL pointer dereference flaw was found in the Linux kernel's Hyper-V VMBus driver in the ACPI resource walking logic. A local user can trigger this issue on systems running under hypervisors that do not provide Hyper-V MMIO ranges in the VMBus ACPI device hierarchy, causing the driver to walk up to the ACPI root object and attempt to dereference its all-ones handle. This results in a NULL pointer dereference in the ACPI subsystem, leading to a kernel crash and denial of service during boot.
Statement
The VMBus driver walks the ACPI namespace from the VMBus device upward searching for Hyper-V MMIO resource ranges. When these ranges are not found in the device or its ancestors, the code continues walking until it reaches the ACPI namespace root object, which has a special all-ones handle value. Attempting to use this handle causes the ACPI code to dereference a NULL pointer (from adding an offset to NULL). This occurs with VMBus implementations that don't provide these MMIO ranges, such as QEMU's VMBus emulation. The ranges appear to be optional since Windows guests function without them. The crash occurs during boot when the VMBus driver probes, affecting Linux guests under KVM/QEMU when using Hyper-V paravirtualization interfaces.
Mitigation
To mitigate this issue, prevent the hv_vmbus module from being loaded. See https://access.redhat.com/solutions/41278 for instructions on blacklisting kernel modules.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | 5.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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