CVE-2026-72151

Technical Description

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

tpm: tpm2-sessions: wait for async KPP completion in tpm_buf_append_salt

tpm_buf_append_salt() in drivers/char/tpm/tpm2-sessions.c calls

crypto_kpp_generate_public_key() and crypto_kpp_compute_shared_secret()

without installing a completion callback, discards both return values,

and immediately frees the kpp_request via kpp_request_free(). When the

resolved ecdh-nist-p256 KPP backend is asynchronous (atmel-ecc, HPRE,

keembay-ocs), either operation returns -EINPROGRESS and the deferred

completion worker dereferences the freed request.

The path fires automatically from the hwrng_fillfn kernel thread via

tpm_get_random -> tpm2_get_random -> tpm2_start_auth_session ->

tpm_buf_append_salt on every entropy poll, without any userland action.

Install crypto_req_done as the completion callback, wrap both KPP

operations in crypto_wait_req(), and propagate errors to the caller.

The wait is a no-op for synchronous backends.

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