CVE-2024-49867

A flaw was found in the Linux kernel's btrfs file system. During an unmount operation, the cleaner kernel thread's resources are prematurely released while fixup workers are still active. This can lead to a use-after-free vulnerability when a fixup worker attempts to access the freed resources. A local user could potentially exploit this to cause a system crash, resulting in a denial of service.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, if the btrfs filesystem is not in use, prevent the btrfs kernel module from loading. This can be achieved by creating a blacklist file.

1. Create a file named /etc/modprobe.d/blacklist-btrfs.conf with the following content:

   blacklist btrfs
   install btrfs /bin/true
   

2. Regenerate the initramfs to ensure the blacklist is applied during boot:

   sudo dracut -f -v
   

3. Reboot the system for the changes to take effect. This mitigation will prevent the btrfs module from loading, which may impact systems that rely on btrfs for storage.