CVE-2022-50520
Description
A reference leak flaw was found in the Linux kernel's Radeon graphics driver in the BIOS retrieval logic. A local user on systems with AMD Radeon graphics hardware can trigger this issue when the driver searches for ACPI firmware tables and exits the search loop with an acquired PCI device reference that is never released. This results in a permanent reference leak preventing proper device cleanup and leading to resource exhaustion or denial of service.
Statement
The radeon_atrm_get_bios function uses pci_get_class to iterate through PCI devices searching for compatible ACPI firmware tables. The pci_get_class function returns a device pointer with an incremented reference count and decrements the reference for the previous device. When the loop breaks with a non-NULL pdev (having found a suitable device), the code fails to call pci_dev_put to decrement the reference count. This violates PCI device reference counting rules and prevents the device from being properly cleaned up even when the driver is unloaded.
Mitigation
To mitigate this issue, prevent the radeon 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: Resource Consumption (Memory); DoS: Resource Consumption (Other)
An adversary that can cause a resource counter to become inaccurate may be able to create situations where resources are not accounted for and not released, thus causing resources to become scarce for future needs.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An adversary that can cause a resource counter to become inaccurate may be able to force an error that causes the product to crash or exit out of its current operation.
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