CyberRota Analysis
AI-GeneratedThe vulnerability affects the Linux kernel's TPM (Trusted Platform Module) subsystem, specifically in the `tpm_buf_append_salt()` function, which improperly handles asynchronous key generation and shared secret computation. This flaw can lead to dereferencing a freed request object, potentially causing system instability or crashes during entropy polling operations. Organizations utilizing Linux systems with TPM functionality, particularly those relying on asynchronous cryptographic backends, should prioritize patching this issue to maintain system integrity and security.
Original NVD 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.