tpm2: Do not call EVP_PKEY_CTX_set0_rsa_oaep_label() for label of size 0 (OSSL 3)

[JuergenReppSIT]

Openssl 3.0 did return an error if EVP_PKEY_CTX_set0_rsa_oaep_label was called
with label size 0. The function should only be called if the size of the label
is greater 0.
With this fix TPM2_RSA_Encrypt/Decrypt did work with OpenSSL 1.1 and 3.0
for encryption without label.

Signed-off-by: Juergen Repp juergen.repp@sit.fraunhofer.de

[coveralls]

Pull Request Test Coverage Report for Build 2427

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.008%) to 77.467%

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Totals
Change from base Build 2421:	0.008%
Covered Lines:	29212
Relevant Lines:	37709

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💛 - Coveralls

[stefanberger]

FYI: This here is the OpenSSL 1.1.1 that still allowed label to be NULL: https://github.com/openssl/openssl/blob/OpenSSL_1_1_1-stable/crypto/rsa/rsa_pmeth.c#L545-L550

[stefanberger]

Can you also please adjust the title of the patch to something like tpm2: Do not call EVP_PKEY_CTX_set0_rsa_oaep_label() for label of size 0 (OSSL 3)

[JuergenReppSIT]

FYI: This here is the OpenSSL 1.1.1 that still allowed label to be NULL: https://github.com/openssl/openssl/blob/OpenSSL_1_1_1-stable/crypto/rsa/rsa_pmeth.c#L545-L550
@stefanberger Thank you for the info. Yes in our CI for tss we have three test cases with label size 0 which did always work. During the first tests with Ubuntu 22.04 using libtpms installed via apt the errors did occur.

[stefanberger]

Thanks!