[Qemu-devel] [PATCH 2/2] qtest: fix crash if SIGABRT during qtest_init()

[Stefan Hajnoczi <stefanha@redhat.com>]

If an assertion fails during qtest_init() the SIGABRT handler is
invoked.  This is the correct behavior since we need to kill the QEMU
process to avoid leaking it when the test dies.

The global_qtest pointer used by the SIGABRT handler is currently only
assigned after qtest_init() returns.  This results in a segfault if an
assertion failure occurs during qtest_init().

Move global_qtest assignment inside qtest_init().  Not pretty but let's
face it - the signal handler dependeds on global state.

Reported-by: Marcel Apfelbaum <marcel.a@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 tests/libqtest.c | 3 ++-
 tests/libqtest.h | 4 +---
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/tests/libqtest.c b/tests/libqtest.c
index c9e78aa..f387662 100644
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -120,7 +120,7 @@ QTestState *qtest_init(const char *extra_args)
     qemu_binary = getenv("QTEST_QEMU_BINARY");
     g_assert(qemu_binary != NULL);
 
-    s = g_malloc(sizeof(*s));
+    global_qtest = s = g_malloc(sizeof(*s));
 
     socket_path = g_strdup_printf("/tmp/qtest-%d.sock", getpid());
     qmp_socket_path = g_strdup_printf("/tmp/qtest-%d.qmp", getpid());
@@ -181,6 +181,7 @@ QTestState *qtest_init(const char *extra_args)
 void qtest_quit(QTestState *s)
 {
     sigaction(SIGABRT, &s->sigact_old, NULL);
+    global_qtest = NULL;
 
     kill_qemu(s);
     close(s->fd);
diff --git a/tests/libqtest.h b/tests/libqtest.h
index 9deebdc..7e23a4e 100644
--- a/tests/libqtest.h
+++ b/tests/libqtest.h
@@ -335,8 +335,7 @@ void qtest_add_func(const char *str, void (*fn));
  */
 static inline QTestState *qtest_start(const char *args)
 {
-    global_qtest = qtest_init(args);
-    return global_qtest;
+    return qtest_init(args);
 }
 
 /**
@@ -347,7 +346,6 @@ static inline QTestState *qtest_start(const char *args)
 static inline void qtest_end(void)
 {
     qtest_quit(global_qtest);
-    global_qtest = NULL;
 }
 
 /**
-- 
1.8.5.3