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

[Gerd Hoffmann <kraxel@redhat.com>]

On 05/29/09 11:51, malc wrote:
>> Having qemu_malloc(0) abort is silly.  Returning NULL or returning
>> malloc(1) are both reasonable options.
>
> Dereference of NULL is UB[1] and dereferencing result of malloc(1) will
> just plain work.

malloc(0) itself isn't a bug.  Dereferencing the pointer is.
Code like this:

   buf = qemu_malloc(len);
   memcpy(buf, src, len);

will work perfectly fine when called with len=0 because it will not 
dereference buf for the len=0 case.  abort() in qemu_malloc for size=0 
will fire for no good reason.

> P.S. So far the abort that went into qemu_malloc caught one usage of zero
>       allocation (once again coming from qcow2).

That was a false positive.

cheers,
   Gerd