Re: [Qemu-trivial] [Qemu-devel] [PATCH 2/2] qemu queue: fix uninitialized removals

[Peter Maydell]

On 18 October 2012 11:43, Kevin Wolf <address@hidden> wrote:
> Am 17.10.2012 23:24, schrieb Tim Hardeck:
>> On Wednesday 17 October 2012 17:00:15 Andreas Färber wrote:
>>> Am 14.10.2012 15:08, schrieb Tim Hardeck:
>>>> When calling QTAILQ_REMOVE or QLIST_REMOVE on an unitialized list
>>>> QEMU segfaults.
>>>
>>> Can this be reproduced by a user today? Or is this just fixing the case
>>> that a developer forgot to initialize a list?
>> I am not sure but in this case it happened during an early VNC connection
>> state failure which most likely wouldn't happen to regular users.
>> I triggered it while working on the VNC connection part.
>>
>> The issue could most likely be also fixed in the VNC connection 
>> initialization
>> process but if this changes doesn't have a relevant performance impact they
>> might prevent some other/future crashes.
>
> At the same time, it could be hiding real bugs, where ignoring the
> QLIST_REMOVE() isn't the right fix. I can see your point, but I would be
> careful with making interfaces less strict.

I agree this patch doesn't seem like the right fix. All lists should
be initialised (either via the _INIT macro or statically using the
_HEAD_INITIALIZER macros) before use. If we ever try to do one of
the other operations on an uninitialised list that's a bug which
needs to be tracked down and fixed.

-- PMM