tests: Fix memory leak in tpm-util.c

This patch fixes the following memory leak detected by asan:

Indirect leak of 560320 byte(s) in 136 object(s) allocated from:
    #0 0x556b3b3f9b57 in calloc (/home/stefanb/tmp/qemu-tip/build/tests/qtest/tpm-crb-swtpm-test+0x23fb57)
    #1 0x152b0e96b9b0 in g_malloc0 (/lib64/libglib-2.0.so.0+0x589b0)
    qemu#2 0x556b3b588f61 in parse_object /home/stefanb/tmp/qemu-tip/build/../qobject/json-parser.c:318:12
    qemu#3 0x556b3b588f61 in parse_value /home/stefanb/tmp/qemu-tip/build/../qobject/json-parser.c:546:16
    qemu#4 0x556b3b5886e8 in json_parser_parse /home/stefanb/tmp/qemu-tip/build/../qobject/json-parser.c:580:14
    qemu#5 0x556b3b52ff4a in json_message_process_token /home/stefanb/tmp/qemu-tip/build/../qobject/json-streamer.c:92:12
    qemu#6 0x556b3b59896f in json_lexer_feed_char /home/stefanb/tmp/qemu-tip/build/../qobject/json-lexer.c:313:13
    qemu#7 0x556b3b598443 in json_lexer_feed /home/stefanb/tmp/qemu-tip/build/../qobject/json-lexer.c:350:9
    qemu#8 0x556b3b436c70 in qmp_fd_receive /home/stefanb/tmp/qemu-tip/build/../tests/qtest/libqtest.c:614:9
    qemu#9 0x556b3b435871 in qtest_qmp_receive_dict /home/stefanb/tmp/qemu-tip/build/../tests/qtest/libqtest.c:636:12
    qemu#10 0x556b3b435871 in qtest_qmp_receive /home/stefanb/tmp/qemu-tip/build/../tests/qtest/libqtest.c:624:27
    qemu#11 0x556b3b435c59 in qtest_vqmp /home/stefanb/tmp/qemu-tip/build/../tests/qtest/libqtest.c:715:12
    qemu#12 0x556b3b435c59 in qtest_qmp /home/stefanb/tmp/qemu-tip/build/../tests/qtest/libqtest.c:756:16
    qemu#13 0x556b3b4328c7 in tpm_util_wait_for_migration_complete /home/stefanb/tmp/qemu-tip/build/../tests/qtest/tpm-util.c:245:15
    qemu#14 0x556b3b4333be in tpm_test_swtpm_migration_test /home/stefanb/tmp/qemu-tip/build/../tests/qtest/tpm-tests.c:117:5
    qemu#15 0x152b0e98e29d  (/lib64/libglib-2.0.so.0+0x7b29d)

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210115204637.3332555-1-stefanb@linux.vnet.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/qtest/tpm-util.c

@@ -250,7 +250,7 @@ void tpm_util_wait_for_migration_complete(QTestState *who)
         status = qdict_get_str(rsp_return, "status");
         completed = strcmp(status, "completed") == 0;
         g_assert_cmpstr(status, !=,  "failed");
-        qobject_unref(rsp_return);
+        qobject_unref(rsp);
         if (completed) {
             return;
         }