CVE-2024-50217
Description
A flaw was found in the Linux kernel's btrfs filesystem. A local attacker could exploit a use-after-free (UAF) vulnerability by mounting two btrfs images with identical filesystem IDs but different device universally unique identifiers (UUIDs) in a specific sequence. This could lead to memory corruption, potentially allowing for privilege escalation or causing a system crash (denial of service).
Mitigation
To mitigate this issue, if the Btrfs filesystem is not in use, the `btrfs` kernel module can be blacklisted to prevent it from being loaded. This can be achieved by creating a modprobe configuration file.
Create `/etc/modprobe.d/blacklist-btrfs.conf` with the following content:
`blacklist btrfs`
After creating the file, regenerate the initramfs and reboot the system for the changes to take effect.
`dracut -f -v`
`reboot`
Warning: Blacklisting the `btrfs` module will prevent the system from mounting or using any Btrfs filesystems. Ensure that no critical system components or data rely on Btrfs before applying this mitigation.
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 | 7.8 | 7.8 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | None |
| User Interaction | None | None | Required |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:N/UI:R/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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