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

[malc <av1474@comtv.ru>]

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.

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