tpm: Use kfree_sensitive() to free auth session in tpm_dev_release()

CVE-2026-46283

What is CVE-2026-46283?

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

tpm: Use kfree_sensitive() to free auth session in tpm_dev_release()

tpm_dev_release() uses plain kfree() to free chip->auth, which contains sensitive cryptographic material including HMAC session keys, nonces, and passphrase data (struct tpm2_auth).

Every other code path that frees this structure uses kfree_sensitive() to zero the memory before releasing it: both tpm2_end_auth_session() and tpm_buf_check_hmac_response() do so. The tpm_dev_release() path is the only one that does not, leaving key material in freed slab memory until it is eventually overwritten.

Use kfree_sensitive() for consistency with the rest of the driver and to ensure session keys are scrubbed during device teardown.

References