CVE-2024-50043

A flaw was found in the Linux kernel's nfsd component. When multiple FREE_STATEIDs are sent for the same delegation stateid, a race condition can occur in the nfsd4_free_stateid() function. This allows the stateid to be accessed again after it has been prematurely released, leading to a use-after-free condition or a counter refcount underflow. This memory corruption vulnerability can result in system instability or a denial of service (DoS).

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 vulnerability, restrict network access to the NFS service to only trusted clients or networks. This can be achieved by configuring firewall rules.

For systems using firewalld: firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<TRUSTED_NETWORK>" port port="2049" protocol="tcp" accept' firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<TRUSTED_NETWORK>" port port="2049" protocol="udp" accept' firewall-cmd --reload

Replace <TRUSTED_NETWORK> with the IP address or network range of your trusted NFS clients. This action may impact legitimate NFS clients if not configured correctly. Reloading the firewall service is required for changes to take effect.