[libvirt] [PATCH] qemu:json: Fix daemon crash on handling domain shutdown event

[Erik Skultety]

On Tue, May 30, 2017 at 10:53:44AM +0200, Peter Krempa wrote:
> On Tue, May 30, 2017 at 10:41:17 +0200, Erik Skultety wrote:
> > commit a8eba5036 added further checking of the guest shutdown cause, but
> > this enhancement is available since qemu 2.10, causing a crash because
> > of a NULL pointer dereference on older qemus.
> >
> > Thread 1 "libvirtd" received signal SIGSEGV, Segmentation fault.
> > 0x00007ffff72441af in virJSONValueObjectGet (object=0x0,
> >                                              key=0x7fffd5ef11bf "guest")
> >     at util/virjson.c:769
> > 769	    if (object->type != VIR_JSON_TYPE_OBJECT)
> > (gdb) bt
> > 0  in virJSONValueObjectGet
> > 1  in virJSONValueObjectGetBoolean
> > 2  in qemuMonitorJSONHandleShutdown
> > 3  in qemuMonitorJSONIOProcessEvent
> > 4  in qemuMonitorJSONIOProcessLine
> > 5  in qemuMonitorJSONIOProcess
> > 6  in qemuMonitorIOProcess
>
> I think you can truncate is somewhere here.
>
> > 7  in qemuMonitorIO
> > 8  in virEventPollDispatchHandles
> > 9  in virEventPollRunOnce
> > 10 in virEventRunDefaultImpl
> > 11 in virNetDaemonRun
> > 12 in main
> >
> > Signed-off-by: Erik Skultety <eskultet at redhat.com>
> > ---
> >  src/qemu/qemu_monitor_json.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
> > index 757595dd7..f208dd05a 100644
> > --- a/src/qemu/qemu_monitor_json.c
> > +++ b/src/qemu/qemu_monitor_json.c
> > @@ -528,7 +528,7 @@ static void qemuMonitorJSONHandleShutdown(qemuMonitorPtr mon, virJSONValuePtr da
> >      bool guest = false;
> >      virTristateBool guest_initiated = VIR_TRISTATE_BOOL_ABSENT;
> >
> > -    if (virJSONValueObjectGetBoolean(data, "guest", &guest) == 0)
> > +    if (data && virJSONValueObjectGetBoolean(data, "guest", &guest) == 0)
> >          guest_initiated = guest ? VIR_TRISTATE_BOOL_YES : VIR_TRISTATE_BOOL_NO;
> >
> >      qemuMonitorEmitShutdown(mon, guest_initiated);
>
> ACK, safe for freeze
>

Adjusted the commit message and pushed, thanks.
Erik