CVE-2025-21871

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

tee: optee: Fix supplicant wait loop

OP-TEE supplicant is a user-space daemon and it's possible for it

be hung or crashed or killed in the middle of processing an OP-TEE

RPC call. It becomes more complicated when there is incorrect shutdown

ordering of the supplicant process vs the OP-TEE client application which

can eventually lead to system hang-up waiting for the closure of the

client application.

Allow the client process waiting in kernel for supplicant response to

be killed rather than indefinitely waiting in an unkillable state. Also,

a normal uninterruptible wait should not have resulted in the hung-task

watchdog getting triggered, but the endless loop would.

This fixes issues observed during system reboot/shutdown when supplicant

got hung for some reason or gets crashed/killed which lead to client

getting hung in an unkillable state. It in turn lead to system being in

hung up state requiring hard power off/

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References