tree 977d0b206d4226f5e631a2b3ded6608c5a7b4476
parent 7be11a790dd8aa761e48f89943afced9bc391e5a
author Gilles Peskine <Gilles.Peskine@arm.com> 1649888235 +0200
committer Gilles Peskine <Gilles.Peskine@arm.com> 1652722674 +0200

psa_raw_key_agreement: return BUFFER_TOO_SMALL when warranted

psa_raw_key_agreement() returned PSA_ERROR_INVALID_ARGUMENT instead of
PSA_ERROR_BUFFER_TOO_SMALL when the output buffer was too small for ECDH,
the only algorithm that is currently implemented. Make it return the correct
error code.

The reason for the wrong error code is that ecdh.c returns
MBEDTLS_ERR_ECP_BAD_INPUT_DATA, presumably for similarith with dhm.c. It
might make sense to change ecdh.c to use MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL,
but dhm.c doesn't have an existing BUFFER_TOO_SMALL error. To minimize the
impact of the fix, handle this in the PSA layer.

Fixes #5735.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>