Re: [Qemu-devel] [PATCH 1/3] qapi: return a 'missing parameter' error

[Markus Armbruster <armbru@redhat.com>]

Marc-André Lureau <mlureau@redhat.com> writes:

> Hi
>
> ----- Original Message -----
>> Aha, we got a different bug fix!  The old code fails to fail when the
>> parameter doesn't exist.  Instead, it sets *obj = NULL, which seems very
>> likely to crash QEMU.  Let me try... yup:
>> 
>>     { "execute": "object-add",
>>       "arguments": { "qom-type": "memory-backend-file", "id": "foo" } }
>> 
>> Kills QEMU with "qemu/qom/object_interfaces.c:115: user_creatable_add_type:
>> Assertion `qdict' failed."
>> 
>> Either fix this in a separate patch before this one, or cover it in this
>> one's commit message.  Your choice.
>> 
>> A separate patch might be usable for qemu-stable.
>
> It looks to me that this is a different bug. 
>
> visit_type_q_obj_object_add_arg_members() doesn't call visit_type_any() if "props" is missing (it's optionnal).
>
> And arg is zero'ed in qmp-marshal, and the assert() was added in ad739706bbadee49. I am trying to fix that regression.

Okay, that's *also* a bug.

For the bug I spotted, try

  { "execute": "qom-set",
    "arguments": { "path": "/machine", "property": "rtc-time" } }

Trips assert(!err != !*obj) in its caller visit_type_any().

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