[libvirt] [PATCH] Fix mem leak in virQEMUCapsProbeQMPMachineTypes on OOM

[Daniel P. Berrange]

On Mon, Nov 11, 2013 at 01:28:04PM +0100, Michal Privoznik wrote:
> On 11.11.2013 12:15, Daniel P. Berrange wrote:
> > From: "Daniel P. Berrange" <berrange at redhat.com>
> > 
> > The virQEMUCapsProbeQMPMachineTypes method iterates over machine
> > types copying them into the qemuCapsPtr object. It only updates
> > the qemuCaps->nmachinetypes value at the end though. So if OOM
> > occurs in the middle, the destructor of qemuCapsPtr will not
> > free the partially initialized machine types.
> > 
> > Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> > ---
> >  src/qemu/qemu_capabilities.c | 11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> > index 71a913b..2712a4d 100644
> > --- a/src/qemu/qemu_capabilities.c
> > +++ b/src/qemu/qemu_capabilities.c
> > @@ -2137,14 +2137,17 @@ virQEMUCapsProbeQMPMachineTypes(virQEMUCapsPtr qemuCaps,
> >          goto cleanup;
> >  
> >      for (i = 0; i < nmachines; i++) {
> > -        if (VIR_STRDUP(qemuCaps->machineAliases[i], machines[i]->alias) < 0 ||
> > -            VIR_STRDUP(qemuCaps->machineTypes[i], machines[i]->name) < 0)
> > +        qemuCaps->nmachineTypes++;
> > +        if (VIR_STRDUP(qemuCaps->machineAliases[qemuCaps->nmachineTypes -1],
> > +                       machines[i]->alias) < 0 ||
> > +            VIR_STRDUP(qemuCaps->machineTypes[qemuCaps->nmachineTypes - 1],
> > +                       machines[i]->name) < 0)
> >              goto cleanup;
> >          if (machines[i]->isDefault)
> >              defIdx = i;
> > -        qemuCaps->machineMaxCpus[i] = machines[i]->maxCpus;
> > +        qemuCaps->machineMaxCpus[qemuCaps->nmachineTypes - 1] =
> > +            machines[i]->maxCpus;
> >      }
> > -    qemuCaps->nmachineTypes = nmachines;
> 
> Wouldn't be sufficient to move this line ^^^ before the for() loop?
> Something like we already have in virQEMUCapsNewCopy().

For this specific case, it would be fine - but the next patch I just
sent causes us to skip some iterations of the loop.  So we need to
calculate it inside the loop.


Daniel
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