Add missing cleanup on failure in psa_key_agreement

If psa_key_derivation_internal() fails, it's up to the caller to clean
up. Do this, and add a note at the top of
psa_key_derivation_internal() and its auxiliary functions.

There is no non-regression test because at the moment the only way to
trigger an error is a borderline low-memory condition and we don't
have the means to trigger this.
This commit is contained in:
Gilles Peskine 2018-11-16 16:05:06 +01:00
parent a05219c70b
commit 346797d7b9

View file

@ -3650,7 +3650,11 @@ exit:
#if defined(MBEDTLS_MD_C)
/* Set up an HKDF-based generator. This is exactly the extract phase
* of the HKDF algorithm. */
* of the HKDF algorithm.
*
* Note that if this function fails, you must call psa_generator_abort()
* to potentially free embedded data structures and wipe confidential data.
*/
static psa_status_t psa_generator_hkdf_setup( psa_hkdf_generator_t *hkdf,
const uint8_t *secret,
size_t secret_length,
@ -3689,7 +3693,11 @@ static psa_status_t psa_generator_hkdf_setup( psa_hkdf_generator_t *hkdf,
#endif /* MBEDTLS_MD_C */
#if defined(MBEDTLS_MD_C)
/* Set up a TLS-1.2-prf-based generator (see RFC 5246, Section 5). */
/* Set up a TLS-1.2-prf-based generator (see RFC 5246, Section 5).
*
* Note that if this function fails, you must call psa_generator_abort()
* to potentially free embedded data structures and wipe confidential data.
*/
static psa_status_t psa_generator_tls12_prf_setup(
psa_tls12_prf_generator_t *tls12_prf,
const unsigned char *key,
@ -3743,6 +3751,9 @@ static psa_status_t psa_generator_tls12_prf_setup(
}
#endif /* MBEDTLS_MD_C */
/* Note that if this function fails, you must call psa_generator_abort()
* to potentially free embedded data structures and wipe confidential data.
*/
static psa_status_t psa_key_derivation_internal(
psa_crypto_generator_t *generator,
const uint8_t *secret, size_t secret_length,
@ -3927,6 +3938,9 @@ exit:
#define PSA_KEY_AGREEMENT_MAX_SHARED_SECRET_SIZE MBEDTLS_ECP_MAX_BYTES
/* Note that if this function fails, you must call psa_generator_abort()
* to potentially free embedded data structures and wipe confidential data.
*/
static psa_status_t psa_key_agreement_internal( psa_crypto_generator_t *generator,
key_slot_t *private_key,
const uint8_t *peer_key,
@ -3984,10 +3998,13 @@ psa_status_t psa_key_agreement( psa_crypto_generator_t *generator,
PSA_KEY_USAGE_DERIVE, alg );
if( status != PSA_SUCCESS )
return( status );
return( psa_key_agreement_internal( generator,
slot,
peer_key, peer_key_length,
alg ) );
status = psa_key_agreement_internal( generator,
slot,
peer_key, peer_key_length,
alg );
if( status != PSA_SUCCESS )
psa_generator_abort( generator );
return( status );
}