Re: [libvirt] [PATCH] virBitmapFree: Change the function to a macro

-----Original Message----- From: Daniel P. Berrange [mailto:berrange@redhat.com] Sent: Friday, September 06, 2013 6:37 PM To: Liuji (Jeremy) Cc: libvir-list(a)redhat.com; Jinbo (Justin); Luohao (brian); Haofeng Subject: Re: [libvirt] [PATCH] virBitmapFree: Change the function to a macro On Fri, Sep 06, 2013 at 10:30:56AM +0000, Liuji (Jeremy) wrote: > The parameter of virBitmapFree function is just a pointer, not a pointer of pointer. > The second VIR_FREE on virBitmapFree only assign NULL to the formal parameter. > After calling the virBitmapFree function, the actual parameter are still not NULL. > There are many code segment don't assign NULL to the formal parameter after calling > the virBitmapFree function. This will bring potential risks. > > A problem scenario: > 1) The XML of VM contain the below segment: > <numatune> > <memory mode='preferred' placement='auto' nodeset='0'/> > </numatune> > 2)virsh create the VM > 3)In the virDomainDefParseXML funtion: > /* Ignore 'nodeset' if 'placement' is 'auto' finally */ > if (placement_mode == VIR_NUMA_TUNE_MEM_PLACEMENT_MODE_AUTO) { > virBitmapFree(def->numatune.memory.nodemask); > def->numatune.memory.nodemask = NULL; > } > 4)Then, virsh destroy the VM. In the virDomainDefFree funtion, it also call the > virBitmapFree function to free the nodemask: > virBitmapFree(def->numatune.memory.nodemask); > But after this call, the value of def->numatune.memory.nodemask is still not NULL. > This will generate an exception. Have you got an actual crash happening today, or is this just a theoretical problem you're trying to address ?