CVE-2021-4460
Description
A flaw was found in the Linux kernel’s AMD Kernel Fusion Driver (amdkfd) within the drm subsystem. When either get_num_sdma_queues() or get_num_xgmi_sdma_queues() returned 0, the driver performed a bit shift where the number of bits shifted equaled the operand width. Such a shift is undefined behavior in C and can lead to incorrect values being used in subsequent logic.A local user with the ability to exercise the affected kernel APIs could trigger unintended behavior in the DRM/AMD GPU driver, which may result in a kernel crash and impact system availability
Mitigation
To mitigate this issue, the `amdkfd` kernel module can be prevented from loading by blacklisting it. Create a file `/etc/modprobe.d/blacklist-amdkfd.conf` with the content `blacklist amdkfd`. A system reboot is required for this change to take effect. This may impact functionality that relies on the AMDGPU kernel graphics driver.
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 | 7.1 | 7.1 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | High | High |
| Integrity Impact | None | None | None |
| Availability Impact | High | High | High |
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:H/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: DoS: Crash, Exit, or Restart
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
