CVE-2023-54107
Description
A flaw was found in the Linux kernel's block cgroup (blk-cgroup) component. A local attacker, by creating and tearing down cgroups and triggering block cgroup policy activity, could exploit a use-after-free vulnerability. This occurs due to the asynchronous execution of pd_free_fn, which can prematurely free parent policy data while child policies may still access it. This could lead to a stale pointer dereference, potentially causing a denial of service (DoS).
Statement
A use after free risk exists in blk cgroup policy data lifetime because pd_free_fn runs asynchronously in blkg_free_workfn and some policies may still access parent policy data through a child even after pd_offline_fn has completed. If the parent blkg reference is dropped too early the parent policy data can be freed before the child cleanup runs. This can lead to a stale pointer dereference when the child cleanup path or policy logic accesses the already freed parent data. For the CVSS the PR:L choice reflects that a local attacker needs the ability to create and tear down cgroups and trigger block cgroup policy activity, which can be delegated in some container setups.
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 | 5.8 | N/A | 7.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | High |
| Integrity Impact | Low | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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