CVE-2025-21871: tee: optee: Fix supplicant wait loop

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-03-27 · updated 2026-06-17
Weakness: CWE-835

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/on to recover.

Affected products

Linux kernel: from 4.12 before 5.4.291; from 5.5 before 5.10.235; from 5.11 before 5.15.179; from 5.16 before 6.1.130; from 6.2 before 6.6.80; from 6.7 before 6.12.17 — fixed in 5.10.235, 5.15.179, 5.4.291, 6.1.130, 6.12.17, 6.13.5

How to fix

Upgrade to a fixed version: Linux kernel 5.10.235, 5.15.179, 5.4.291, 6.1.130. Check the vendor advisory for mitigations.

References

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