Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently

[Kevin Wolf]

malc schrieb:
> On Fri, 29 May 2009, Kevin Wolf wrote:
> 
>> malc schrieb:
>>>> Putting the abort() in there is going to introduce a ton of subtle bugs,
>>>> I vote for changing qemu_malloc() to have a sane behavior.
>>> And those will be caught, given one a chance to analyze things, unlike
>>> head in the sand approach of hoping things would just work.
>>>
>>> After doing some research, after the aforementioned lengthy discussion,
>>> the only free OS that straight-forwardly described what it does was
>>> OpenBSD:
>>>
>>> http://www.openbsd.org/cgi-bin/man.cgi?query=malloc&apropos=0&sektion=0&manpath=OpenBSD+Current&arch=i386&format=html
>>>
>>> P.S. So far the abort that went into qemu_malloc caught one usage of zero
>>>      allocation (once again coming from qcow2).
>> Zero allocation isn't a bug per se. Checking for NULL or dereferencing
>> is. Any value that can be freed, be it NULL or anything else, was
>> perfectly fine here without the abort() patch. So it actually was one of
>> the subtle bugs Anthony mentioned which are introduced by the abort().
> 
> And once again, the code would have aborted on AIX with our without abort
> patch. The reason for abort is to identify and reason about all the call
> sites that do that.

Why would it have aborted? If AIX aborts on malloc(0), its malloc is
seriously broken. But as I have understood from previous discussion, AIX
just returns NULL. Would have been okay for this code.

Kevin