Fix parameter validation for mbedtls_mpi_lsb()
The MPI_VALIDATE_RET() macro cannot be used for parameter
validation of mbedtls_mpi_lsb() because this function returns
a size_t.
Use the underlying MBEDTLS_INTERNAL_VALIDATE_RET() insteaed,
returning 0 on failure.
Also, add a test for this behaviour.
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index 3379a99..d1fa5a4 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -216,6 +216,8 @@
TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
mbedtls_mpi_div_int( &X, &X, NULL, 42 ) );
+ TEST_INVALID_PARAM_RET( 0, mbedtls_mpi_lsb( NULL ) );
+
TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
mbedtls_mpi_mod_mpi( NULL, &X, &X ) );
TEST_INVALID_PARAM_RET( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,