CVE-2024-46687
Description
A flaw was found in the Linux kernel's btrfs filesystem. A local attacker with low privileges could exploit a use-after-free vulnerability when the btrfs_submit_chunk() function encounters errors during I/O operations. This double-freeing issue can lead to memory corruption, potentially allowing the attacker to achieve privilege escalation or cause a denial of service.
Mitigation
To mitigate this issue, prevent the btrfs kernel module from loading if the btrfs filesystem is not in use. This can be achieved by blacklisting the module.
To blacklist the `btrfs` module:
1. Create a file named `/etc/modprobe.d/blacklist-btrfs.conf` with the following content:
blacklist btrfs2. Regenerate the initramfs to ensure the blacklist is applied during boot:
install btrfs /bin/true
bash3. Reboot the system for the changes to take effect.
sudo dracut -f -v
Warning: Blacklisting the `btrfs` module will prevent any btrfs filesystems from being mounted. Ensure that no critical system partitions or data volumes rely on btrfs before applying this mitigation. A system reboot is required for the changes to be fully effective.
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 | Low |
| User Interaction | None | None | None |
| 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: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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