tests: Add null checks in torture_pki_ecdsa.c

Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

tests/unittests/torture_pki_ecdsa.c

@@ -289,6 +289,7 @@ static void torture_pki_ecdsa_duplicate_key(void **state)
                                      NULL,
                                      &privkey);
     assert_true(rc == 0);
+    assert_non_null(privkey);
 
     privkey_dup = ssh_key_dup(privkey);
     assert_non_null(privkey_dup);
@@ -445,6 +446,7 @@ static void torture_pki_ecdsa_write_privkey(void **state)
                                      NULL,
                                      &privkey);
     assert_true(rc == 0);
+    assert_non_null(privkey);
 
     rc = ssh_key_cmp(origkey, privkey, SSH_KEY_CMP_PRIVATE);
     assert_true(rc == 0);
@@ -459,6 +461,7 @@ static void torture_pki_ecdsa_write_privkey(void **state)
                                      NULL,
                                      &origkey);
     assert_true(rc == 0);
+    assert_non_null(origkey);
 
     unlink(LIBSSH_ECDSA_TESTKEY_PASSPHRASE);
     rc = ssh_pki_export_privkey_file(origkey,