AMD Power Management Firmware (SMU) - array index validation: An unvalidated array index in AMD's power management

Impact

An unvalidated array index in AMD's power management firmware lets a privileged attacker corrupt AGESA memory. The SMU is a live, always-running microcontroller with broad platform reach, so memory corruption there is an integrity problem for the whole node's power and clock management - including, on GPU nodes, the mechanisms that keep accelerators inside their thermal envelope.

Who can reach it

Local, privileged. Reachable through the SMU mailbox interface, which requires root.

What to do

Fixed in AMD reference firmware (AGESA / SEV firmware) and delivered to you only as an OEM SBIOS/BIOS package - Dell, HPE, Supermicro, Lenovo, Gigabyte and the ODMs each rebuild and requalify AMD's AGESA drop before it ships. **Expect months, not weeks**: AMD publishes the bulletin, the OEM ships BIOS somewhere between one and six months later, and for platforms past their support window it may never arrive at all. Applying it is a full node power cycle with the host drained - not a driver reload, not a live patch. Track it as a firmware campaign per server SKU, not per kernel version, and verify afterwards by reading back the SMU/PSP firmware version rather than trusting the BIOS revision string. SMU firmware ships inside the SBIOS/AGESA bundle - there is no separate SMU update channel you can drive yourself.

References