CVE-2023-53576
Description
A missing validation flaw was found in the Linux kernel null_blk driver's configuration handling. A local user with access to configfs can configure a null_blk device with queue_mode set to 1 (legacy I/O path), which is no longer supported, causing the driver to proceed without proper validation and triggering a kernel oops and denial of service through system crash.
Statement
The null_validate_conf() function fails to check the device queue mode setting when configured via configfs. When userspace sets queue_mode to 1 (NULL_Q_RQ, representing the legacy request-based I/O path), the driver should reject this configuration since the legacy path has been removed. Instead, the driver accepts the invalid mode and attempts to initialize with it, causing a kernel oops when the incompatible code paths execute.
Mitigation
To mitigate this issue, prevent the null_blk module from loading. 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)
Other
Technical Impact: Varies by Context
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