Further improve/fix ec_GFp_simple_points_make_affine (ecp_smpl.c) and

group_order_tests (ectest.c).  Also fix the EC_POINTs_mul documentation (ec.h).

Reviewed-by: emilia@openssl.org

crypto/ec/ec.h

@@ -633,7 +633,7 @@ int EC_POINT_cmp(const EC_GROUP *group, const EC_POINT *a, const EC_POINT *b, BN
 int EC_POINT_make_affine(const EC_GROUP *group, EC_POINT *point, BN_CTX *ctx);
 int EC_POINTs_make_affine(const EC_GROUP *group, size_t num, EC_POINT *points[], BN_CTX *ctx);
 
-/** Computes r = generator * n sum_{i=0}^num p[i] * m[i]
+/** Computes r = generator * n sum_{i=0}^{num-1} p[i] * m[i]
  *  \param  group  underlying EC_GROUP object
  *  \param  r      EC_POINT object for the result
  *  \param  n      BIGNUM with the multiplier for the group generator (optional)

crypto/ec/ecp_smpl.c

@@ -1311,8 +1311,8 @@ int ec_GFp_simple_points_make_affine(const EC_GROUP *group, size_t num, EC_POINT
 		{
 		for (i = 0; i < num; i++)
 			{
-			if (prod_Z[i] != NULL)
-				BN_clear_free(prod_Z[i]);
+			if (prod_Z[i] == NULL) break;
+			BN_clear_free(prod_Z[i]);
 			}
 		OPENSSL_free(prod_Z);
 		}

crypto/ec/ectest.c

@@ -251,14 +251,15 @@ static void group_order_tests(EC_GROUP *group)
 		if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
 
 		/* Exercise EC_POINTs_mul, including corner cases. */
+		if (EC_POINT_is_at_infinity(group, P)) ABORT;
 		scalars[0] = n1; points[0] = Q; /* => infinity */
 		scalars[1] = n2; points[1] = P; /* => -P */
 		scalars[2] = n1; points[2] = Q; /* => infinity */
 		scalars[3] = n2; points[3] = Q; /* => infinity */
 		scalars[4] = n1; points[4] = P; /* => P */
 		scalars[5] = n2; points[5] = Q; /* => infinity */
-		if (!EC_POINTs_mul(group, Q, NULL, 5, points, scalars, ctx)) ABORT;
-		if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
+		if (!EC_POINTs_mul(group, P, NULL, 6, points, scalars, ctx)) ABORT;
+		if (!EC_POINT_is_at_infinity(group, P)) ABORT;
 		}
 	fprintf(stdout, "ok\n");