mpi: Allow opaque MPI with zero length.

* mpi/mpiutil.c (_gcry_mpi_copy): Support zero length.

--

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/mpi/mpiutil.c b/mpi/mpiutil.c
index a5583c79..74fbac37 100644
--- a/mpi/mpiutil.c
+++ b/mpi/mpiutil.c
@@ -366,10 +366,13 @@ _gcry_mpi_copy (gcry_mpi_t a)
     gcry_mpi_t b;
 
     if( a && (a->flags & 4) ) {
-        void *p = _gcry_is_secure(a->d)? xmalloc_secure ((a->sign+7)/8)
-                                       : xmalloc ((a->sign+7)/8);
-        if (a->d)
-          memcpy( p, a->d, (a->sign+7)/8 );
+        void *p = NULL;
+        if (a->sign) {
+            p = _gcry_is_secure(a->d)? xmalloc_secure ((a->sign+7)/8)
+                                     : xmalloc ((a->sign+7)/8);
+            if (a->d)
+                memcpy( p, a->d, (a->sign+7)/8 );
+        }
         b = mpi_set_opaque( NULL, p, a->sign );
         b->flags = a->flags;
         b->flags &= ~(16|32); /* Reset the immutable and constant flags.  */