Do not leave COBJ-ified mp_int uninitialized.

Here we ensure that the digits pointer of an uninitialized
mp_int is nulled out.  The garbage collector could conceivably
encounter such an object, in which case mp_clear will then try
to free a garbage pointer. This could happen if an exception
is thrown out of numeric code due to low memory, interrupting
its execution, leaving behind an unfilled object produced
by make_ubignum.

* arith.c (make_ubignum): Perform minimal
initialization of the mp_int using new function.

* mpi/mpi.h (mp_init_minimal): New inline function.

1 files changed, 5 insertions, 0 deletions

diff --git a/mpi/mpi.h b/mpi/mpi.h
index cd7e823d..aac49019 100644
--- a/mpi/mpi.h
+++ b/mpi/mpi.h
@@ -85,6 +85,11 @@ void         mp_set_prec(unsigned int prec);
 /* Memory management                                                      */
 
 mp_err mp_init(mp_int *mp);
+INLINE mp_err mp_init_minimal(mp_int *mp)
+{
+  DIGITS(mp) = 0;
+  return MP_OKAY;
+}
 mp_err mp_init_array(mp_int mp[], int count);
 mp_err mp_init_size(mp_int *mp, mp_size prec);
 mp_err mp_init_copy(mp_int *mp, mp_int *from);