daemon: Fix segfault by reloading daemon right after start

Libvirt could crash with segfault if user issue "service reload" right
after "service start". One possible way to crash libvirt is to run reload
during initialization of QEMU driver.

It could happen when qemu driver will initialize qemu_driver_lock but
don't have a time to set it's "config" and the SIGHUP arrives. The
reload handler tries to get qemu_drv->config during "virStorageAutostart"
and dereference it which ends with segfault.

Let's ignore all reload requests until all drivers are initialized. In
addition set driversInitialized before we enter virStateCleanup to
ignore reload request while we are shutting down.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1179981

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>

diff --git a/daemon/libvirtd.c b/daemon/libvirtd.c
index 86accaa3bcbfa7b38a4823096ad85935c44665ed..2366d63cd3c70f75df5af82d2c241df163293eab 100644 (file)
--- a/daemon/libvirtd.c
+++ b/daemon/libvirtd.c
@@ -785,6 +785,11 @@ static void daemonReloadHandler(virNetServerPtr srv ATTRIBUTE_UNUSED,
                                 siginfo_t *sig ATTRIBUTE_UNUSED,
                                 void *opaque ATTRIBUTE_UNUSED)
 {
+    if (!driversInitialized) {
+        VIR_WARN("Drivers are not initialized, reload ignored");
+        return;
+    }
+
     VIR_INFO("Reloading configuration on SIGHUP");
     virHookCall(VIR_HOOK_DRIVER_DAEMON, "-",
                 VIR_HOOK_DAEMON_OP_RELOAD, SIGHUP, "SIGHUP", NULL, NULL);
@@ -1519,8 +1524,10 @@ int main(int argc, char **argv) {
 
     daemonConfigFree(config);
 
-    if (driversInitialized)
+    if (driversInitialized) {
+        driversInitialized = false;
         virStateCleanup();
+    }
 
     return ret;
 }