Lustre ptlrpc / mdt modules (client-driven server panic family): FABRIC DOS: the head of a family of ten Lustre defects

Impact

FABRIC DOS: the head of a family of ten Lustre defects (CVE-2019-20423 through CVE-2019-20432) that all share one shape — the server does not validate fields in packets sent by a client, so any client can panic the metadata or object storage server with a malformed RPC. Ten separate ways for one tenant's node to take down the filesystem that every other tenant's training job is reading from. In a shared-storage AI cluster this is the cheapest available cross-tenant denial of service: one machine, one packet, everyone's jobs stall.

Who can reach it

Any mounted Lustre client. No credentials, no escalation — the client is inherently trusted by the protocol.

What to do

Upgrade Lustre servers to 2.12.3 or later and restart the MDS/OSS nodes; failover pairs limit but do not eliminate the I/O pause. There is no config workaround for the parsing itself. What you can do immediately is network-level: restrict which hosts can reach LNet, and stop treating 'the tenant's compute node' as a trusted peer of your storage servers.

References