CVE-2023-53541
Description
A buffer overflow vulnerability was found in the Linux kernel's Broadcom NAND controller driver when writing out-of-band data. When the OOB buffer length isn't a multiple of word size, the write function performs an out-of-bounds read on the source buffer during its final iteration. This can read beyond allocated memory and potentially cause memory corruption or crashes, resulting in denial of service.
Statement
NAND flash uses OOB (out-of-band) areas to store metadata like error correction codes alongside the main data. The Broadcom NAND driver's OOB write function processes this data in word-sized chunks for efficiency. However, when the OOB buffer size isn't evenly divisible by the word size, the final iteration of the write loop doesn't have a full word of data available. The code still attempts to read a complete word from the source buffer, reading past the buffer's end into whatever memory happens to follow it. Depending on what lies beyond the buffer, this could read uninitialized memory, crash due to page faults, or incorporate garbage values into the OOB data written to flash. The fix adds explicit length checks and pads with 0xff (the NAND erase value) when reaching the buffer end. This primarily affects systems using Broadcom NAND controllers with OOB operations.
Mitigation
To mitigate this issue, prevent the brcmnand module from being loaded. 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).
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 | 7.8 | 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 | High | N/A |
| Integrity Impact | None | High | 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:H/I:H/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
