A flaw was found in the implementation of the 9p filesystem in the Linux kernel. The 9p filesystem does not protect i_size_write() properly, which causes an i_size_read() infinite loop. An attacker, able to mount a specially crafted filesystem, could cause a denial of service on SMP systems.

Mitigation

As the 9p module will be auto-loaded when required, its use can be disabled by preventing the module from loading with the following instructions:

echo "install 9p /bin/true" >> /etc/modprobe.d/disable-9p.conf

The system will need to be restarted if the 9p modules are loaded. In most circumstances, the 9p kernel modules will be unable to be unloaded while the filesystems are 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.