Fix NULL deference when validating FFC public key.

Fixes CVE-2023-0217

When attempting to do a BN_Copy of params->p there was no NULL check.
Since BN_copy does not check for NULL this is a NULL reference.

As an aside BN_cmp() does do a NULL check, so there are other checks
that fail because a NULL is passed. A more general check for NULL params
has been added for both FFC public and private key validation instead.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
This commit is contained in:
slontis 2023-01-11 11:05:04 +10:00 committed by Tomas Mraz
parent 3436f9c24a
commit bcec03c33c
3 changed files with 41 additions and 0 deletions

View File

@ -24,6 +24,11 @@ int ossl_ffc_validate_public_key_partial(const FFC_PARAMS *params,
BN_CTX *ctx = NULL;
*ret = 0;
if (params == NULL || pub_key == NULL || params->p == NULL) {
*ret = FFC_ERROR_PASSED_NULL_PARAM;
return 0;
}
ctx = BN_CTX_new_ex(NULL);
if (ctx == NULL)
goto err;
@ -107,6 +112,10 @@ int ossl_ffc_validate_private_key(const BIGNUM *upper, const BIGNUM *priv,
*ret = 0;
if (priv == NULL || upper == NULL) {
*ret = FFC_ERROR_PASSED_NULL_PARAM;
goto err;
}
if (BN_cmp(priv, BN_value_one()) < 0) {
*ret |= FFC_ERROR_PRIVKEY_TOO_SMALL;
goto err;

View File

@ -76,6 +76,7 @@
# define FFC_ERROR_NOT_SUITABLE_GENERATOR 0x08
# define FFC_ERROR_PRIVKEY_TOO_SMALL 0x10
# define FFC_ERROR_PRIVKEY_TOO_LARGE 0x20
# define FFC_ERROR_PASSED_NULL_PARAM 0x40
/*
* Finite field cryptography (FFC) domain parameters are used by DH and DSA.

View File

@ -510,6 +510,27 @@ static int ffc_public_validate_test(void)
if (!TEST_true(ossl_ffc_validate_public_key(params, pub, &res)))
goto err;
/* Fail if params is NULL */
if (!TEST_false(ossl_ffc_validate_public_key(NULL, pub, &res)))
goto err;
if (!TEST_int_eq(FFC_ERROR_PASSED_NULL_PARAM, res))
goto err;
res = -1;
/* Fail if pubkey is NULL */
if (!TEST_false(ossl_ffc_validate_public_key(params, NULL, &res)))
goto err;
if (!TEST_int_eq(FFC_ERROR_PASSED_NULL_PARAM, res))
goto err;
res = -1;
BN_free(params->p);
params->p = NULL;
/* Fail if params->p is NULL */
if (!TEST_false(ossl_ffc_validate_public_key(params, pub, &res)))
goto err;
if (!TEST_int_eq(FFC_ERROR_PASSED_NULL_PARAM, res))
goto err;
ret = 1;
err:
DH_free(dh);
@ -567,6 +588,16 @@ static int ffc_private_validate_test(void)
if (!TEST_true(ossl_ffc_validate_private_key(params->q, priv, &res)))
goto err;
if (!TEST_false(ossl_ffc_validate_private_key(NULL, priv, &res)))
goto err;
if (!TEST_int_eq(FFC_ERROR_PASSED_NULL_PARAM, res))
goto err;
res = -1;
if (!TEST_false(ossl_ffc_validate_private_key(params->q, NULL, &res)))
goto err;
if (!TEST_int_eq(FFC_ERROR_PASSED_NULL_PARAM, res))
goto err;
ret = 1;
err:
DH_free(dh);