A flaw was found in the BTRFS implementation in the Linux kernel, where a local user with elevated permissions (either root user or in the disk group) can issue an ioctl to the /dev/btrfs-control device node. This flaw panics the system and allows memory allocation if a specially crafted ioctl is made that abuses the logic when comparing values with different types.

Mitigation

As the BTRFS module will be auto-loaded when required, its use can be disabled by preventing the module from loading with the following instructions:

echo "install btrfs /bin/true" >> /etc/modprobe.d/disable-btrfs.conf

The system will need to be restarted if the BTRFS modules are loaded, it may be possible to unload them. In most circumstances, the BTRFS kernel modules will be unable to be unloaded while any BTRFS filesystems are mounted or in use.

If the system requires this module to work correctly, this mitigation may not be suitable.

If you need further assistance, see KCS article <https://access.redhat.com/solutions/41278&gt; or contact Red Hat Global Support Services.