[libvirt] [PATCH v2 1/2] daemon: Fix segfault by reloading daemon right after start

[Pavel Hrdina]

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 at redhat.com>
---

diff to v1:
 - ignore reload also during virStateCleanup

 daemon/libvirtd.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/daemon/libvirtd.c b/daemon/libvirtd.c
index 86accaa..2366d63 100644
--- 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;
 }
-- 
2.0.5