Merge pull request #6570 from gilles-peskine-arm/bignum-mbedtls_test_read_mpi_core-nonempty
Forbid empty mpi_core in test data
diff --git a/library/constant_time_internal.h b/library/constant_time_internal.h
index 9cc63c2..1e4a3ab 100644
--- a/library/constant_time_internal.h
+++ b/library/constant_time_internal.h
@@ -138,6 +138,7 @@
* \param B The right-hand MPI. This must point to an array of limbs
* with the same allocated length as \p A.
* \param limbs The number of limbs in \p A and \p B.
+ * This must not be 0.
*
* \return The result of the comparison:
* \c 1 if \p A is less than \p B.
diff --git a/tests/src/helpers.c b/tests/src/helpers.c
index b7c8364..cc23fd7 100644
--- a/tests/src/helpers.c
+++ b/tests/src/helpers.c
@@ -357,8 +357,12 @@
size_t hex_len = strlen( input );
size_t byte_len = ( hex_len + 1 ) / 2;
*plimbs = CHARS_TO_LIMBS( byte_len );
+
+ /* A core bignum is not allowed to be empty. Forbid it as test data,
+ * this way static analyzers have a chance of knowing we don't expect
+ * the bignum functions to support empty inputs. */
if( *plimbs == 0 )
- return( 0 );
+ return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
*pX = mbedtls_calloc( *plimbs, sizeof( **pX ) );
if( *pX == NULL )
diff --git a/tests/suites/test_suite_bignum_core.misc.data b/tests/suites/test_suite_bignum_core.misc.data
index 30c767c..62480e4 100644
--- a/tests/suites/test_suite_bignum_core.misc.data
+++ b/tests/suites/test_suite_bignum_core.misc.data
@@ -167,9 +167,6 @@
mbedtls_mpi_core_lt_ct: x<y (1 limb)
mpi_core_lt_ct:"2B5":"2B6":1
-mbedtls_mpi_core_lt_ct: x=y (0 limbs)
-mpi_core_lt_ct:"":"":0
-
mbedtls_mpi_core_lt_ct: x>y (63 bit x, y first byte greater)
mpi_core_lt_ct:"7FFFFFFFFFFFFFFF":"00000000000000FF":0