CVE-2023-53671
Description
A synchronization flaw was found in the Linux kernel Sleepable Read-Copy-Update (SRCU) implementation. The subsystem assumed that central processing unit (CPU) 0 was always online. On systems where CPU 0 is offline, such as crash-kernel configurations using a different boot CPU, SRCU work could be queued to a non-existent CPU and hang indefinitely, causing a denial of service.
Statement
The problem is not attacker-driven; it is a boot-time topology assumption. SRCU queued synchronization work to CPU 0 even when that CPU was not active. The fix replaces the hard-coded CPU ID with the boot CPU identifier, which is guaranteed to be online, ensuring synchronization work completes properly.
Mitigation
To mitigate this issue, prevent module rcu from being loaded.
Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.
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
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