Merge pull request #797 from LSSTDESC/double_free_bug

Fix double-free bug

pyccl/correlation.py

@@ -95,11 +95,15 @@ def correlation(cosmo, ell, C_ell, theta, type='NN', corr_type=None,
         scalar = True
         theta = np.array([theta, ])
 
-    # Call correlation function
-    wth, status = lib.correlation_vec(cosmo, ell, C_ell, theta,
-                                      correlation_types[type],
-                                      correlation_methods[method],
-                                      len(theta), status)
+    if np.all(np.array(C_ell) == 0):
+        # short-cut and also avoid integration errors
+        wth = np.zeros_like(theta)
+    else:
+        # Call correlation function
+        wth, status = lib.correlation_vec(cosmo, ell, C_ell, theta,
+                                          correlation_types[type],
+                                          correlation_methods[method],
+                                          len(theta), status)
     check(status, cosmo_in)
     if scalar:
         return wth[0]

pyccl/tests/test_correlation.py

@@ -1,6 +1,7 @@
 import numpy as np
 import pyccl as ccl
 import pytest
+from timeit import default_timer
 
 COSMO = ccl.Cosmology(
     Omega_c=0.27, Omega_b=0.045, h=0.67, sigma8=0.8, n_s=0.96,
@@ -129,3 +130,26 @@ def test_correlation_raises():
         ccl.correlation(COSMO, [1], [1e-3], [1], type='blah')
     with pytest.raises(ValueError):
         ccl.correlation(COSMO, [1], [1e-3], [1], corr_type='blah')
+
+
+def test_correlation_zero():
+    ell = np.arange(2, 100000)
+    C_ell = np.zeros(ell.size)
+    theta = np.logspace(0, 2, 10000)
+    t0 = default_timer()
+    corr = ccl.correlation(COSMO, ell, C_ell, theta)
+    t1 = default_timer()
+    # if the short-cut has worked this should take
+    # less than 1 second at the absolute outside
+    assert t1 - t0 < 1.0
+    assert (corr == np.zeros(theta.size)).all()
+
+
+def test_correlation_zero_ends():
+    # This should give an error instead of crashing
+    ell = np.arange(2, 1001)
+    C_ell = np.zeros(ell.size)
+    C_ell[500] = 1.0
+    theta = np.logspace(0, 2, 20)
+    with pytest.raises(ccl.CCLError):
+        ccl.correlation(COSMO, ell, C_ell, theta)

src/ccl_correlation.c

@@ -71,6 +71,16 @@ static void ccl_tracer_corr_fftlog(ccl_cosmology *cosmo,
 				  ccl_f1d_extrap_const,
 				  ccl_f1d_extrap_logx_logy,
 				  status);
+  if (*status) {
+    free(l_arr);
+    free(cl_arr);
+    ccl_cosmology_set_status_message(cosmo,
+                                     "ccl_correlation.c: ccl_f1d_t_new "
+                                     "failed to create spline\n");
+    if (cl_spl) ccl_f1d_t_free(cl_spl);
+    return;
+  }
+
   if(cl_spl==NULL) {
     free(l_arr);
     free(cl_arr);

src/ccl_f1d.c

@@ -103,6 +103,14 @@ ccl_f1d_t *ccl_f1d_t_new(int n,double *x,double *y,double y0,double yf,
   }
   else // No extrapolation
     spl->der_hi = 0;
+
+  // If one of the derivatives could not be calculated
+  // then return NULL.
+  if (*status){
+    ccl_f1d_t_free(spl);
+    spl = NULL;
+  }
+
   return spl;
 }