CVE-2023-53593
Description
A lock leak flaw was found in the Linux kernel's CIFS filesystem implementation in the fscache read path. A local user can trigger this issue when reading CIFS files with fscache enabled and a cache hit occurs, causing the page lock to never be released. This creates a deadlock where subsequent accesses to the same page block indefinitely waiting for the lock, resulting in hung processes and denial of service that persists until reboot.
Statement
The CIFS filesystem can use fscache to cache file data locally, improving performance for network filesystems. The VFS read_folio contract specifies that the filesystem must unlock the page when reading completes, regardless of success or failure. The cifs_readpage_worker function handles page reads and is responsible for unlocking pages. When fscache is enabled and returns a cache hit through cifs_readpage_from_fscache, the data is retrieved successfully from cache—but the code marks the page clean without releasing its lock. Meanwhile, cifs_readahead (which handles multi-page reads) calls the same fscache function but does unconditionally unlock pages afterward. This asymmetry means single-page reads leak locks while multi-page reads don't. Once leaked, any subsequent attempt to access that page—whether through read, mmap, or page fault—blocks forever waiting for a lock that will never be released. The resulting deadlock requires a full system reboot to clear.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
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 (Other); DoS: Resource Consumption (Memory); DoS: Resource Consumption (CPU)
An attacker that can influence the allocation of resources that are not properly released could deplete the available resource pool and prevent all other processes from accessing the same type of resource. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.
Frequently Asked Questions
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