RSA: Do not set NULL OAEP labels

As of the previous commit, when a zero-length (string) parameter
is present in the parameters passed to a provider for a given operation,
we will produce an object corresponding to that zero-length parameter,
indicating to the underlying cryptographic operation that the parameter
was passed.  However, rsa_cms_decrypt() was relying on the previous
behavior, and unconditionally tried to call
EVP_PKEY_CTX_set0_rsa_oaep_label() even when the implicit default label
was used (and thus the relevant local variable was still NULL).
In the new setup that distinguishes present-but-empty and absent
more clearly, it is an error to attempt to set a NULL parameter,
even if it is zero-length.

Exercise more caution when setting parameters, and do not call
EVP_PKEY_CTX_set0_rsa_oaep_label() when there is not actually a
label provided.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11920)
This commit is contained in:
Benjamin Kaduk 2020-05-22 11:13:24 -07:00 committed by Benjamin Kaduk
parent 7c302f8afc
commit 9c44916ce5

View File

@ -1007,7 +1007,8 @@ static int rsa_cms_decrypt(CMS_RecipientInfo *ri)
goto err;
if (EVP_PKEY_CTX_set_rsa_mgf1_md(pkctx, mgf1md) <= 0)
goto err;
if (EVP_PKEY_CTX_set0_rsa_oaep_label(pkctx, label, labellen) <= 0)
if (label != NULL
&& EVP_PKEY_CTX_set0_rsa_oaep_label(pkctx, label, labellen) <= 0)
goto err;
/* Carry on */
rv = 1;