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.