CVE-2023-53536
Description
A use-after-free vulnerability was found in the Linux kernel block layer crypto key management. When blk_crypto_evict_key() fails due to a key still being in-use or keyslot eviction failure during inode eviction, the function returns an error but leaves the key linked in keyslot management structures, causing the caller to free the blk_crypto_key structure regardless of the error, which results in a use-after-free when other code later accesses the freed key and can lead to memory corruption and denial of service.
Statement
The issue arises because of a mismatch between blk_crypto_evict_key()'s error handling and its callers' expectations. When evicting encryption keys during inode eviction or similar contexts, if blk_crypto_evict_key() detects that a key is still in-use or if the hardware keyslot_evict operation fails, it returns an error while leaving the key linked into the keyslot management lists and trees. However, callers like inode eviction treat failure as non-fatal and proceed to free the blk_crypto_key memory regardless of the return value, since in these contexts failure is not an option. This creates a window where the management structures contain pointers to freed memory. When blk_crypto_reprogram_all_keys() or other functions later traverse these structures, they dereference freed memory, causing use-after-free conditions.
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 | 7.8 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | High | High |
| Integrity Impact | None | High | High |
| Availability Impact | High | High | High |
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:H/I:H/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)
Confidentiality
Technical Impact: Read Memory
If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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