[PATCH] error-report: fix crash when compute iso8061 time

[Lei He <helei.sig11@bytedance.com>]

g_get_real_time() returns the number of MICROSECONDS since
January 1, 1970 UTC, but g_date_time_new_from_unix_utc() expects
a timestamp in SECONDS.

Directly call g_data_time_new_from_unix_utc(g_get_real_time()) causes
overflow and a NULL pointer is returned, then qemu crashes.

Use g_date_time_new_now_utc() instead, and add a check for NULL result.

Signed-off-by: Lei He <helei.sig11@bytedance.com>
---
 util/error-report.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/util/error-report.c b/util/error-report.c
index dbadaf206d..d3c150661d 100644
--- a/util/error-report.c
+++ b/util/error-report.c
@@ -173,10 +173,13 @@ static char *
 real_time_iso8601(void)
 {
 #if GLIB_CHECK_VERSION(2,62,0)
-    g_autoptr(GDateTime) dt = g_date_time_new_from_unix_utc(g_get_real_time());
+    g_autoptr(GDateTime) dt = g_date_time_new_now_utc();
     /* ignore deprecation warning, since GLIB_VERSION_MAX_ALLOWED is 2.56 */
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+    if (!dt) {
+        return NULL;
+    }
     return g_date_time_format_iso8601(dt);
 #pragma GCC diagnostic pop
 #else
@@ -199,8 +202,10 @@ static void vreport(report_type type, const char *fmt, va_list ap)
 
     if (message_with_timestamp && !monitor_cur()) {
         timestr = real_time_iso8601();
-        error_printf("%s ", timestr);
-        g_free(timestr);
+        if (timestr) {
+            error_printf("%s ", timestr);
+            g_free(timestr);
+        }
     }
 
     /* Only prepend guest name if -msg guest-name and -name guest=... are set */
-- 
2.11.0