Re: [Qemu-devel] [PATCH] usb-mtp: Assert on suspicious TYPE_DATA packet from initiator

[Peter Maydell]

On 18 May 2018 at 19:38, Bandan Das <address@hidden> wrote:
> Peter Maydell <address@hidden> writes:
>
>> On 18 May 2018 at 19:22, Bandan Das <address@hidden> wrote:
>>>
>>> CID 1390604
>>> If the initiator sends a packet with TYPE_DATA set without
>>> initiating a CMD_GET_OBJECT_INFO first, then usb_mtp_get_data
>>> can trip on a null s->data_out.
>>>
>>> Signed-off-by: Bandan Das <address@hidden>
>>
>> I think you said this can be provoked by the guest?
>
> Yes, this can only be initated by the guest as far as I
> understand.
>
>> Misbehaving or malicious guests should never be able
>> to provoke assertions.
>
> I am not sure, I thought it's better to kill a misbehaving guest rather
> than silently letting it run. Anyway, it's possible to send a
> No_Valid_ObjectInfo as well and we wouldn't have to mark it as a
> false positive either.

Broadly speaking, where we're emulating hardware we should do
what the hardware does when the guest does wrong things to it.
A real server doesn't suddenly vanish leaving behind a
message saying "assertion failed" :-)

thanks
-- PMM