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Re: [libvirt] new NULL-dereference in qemu_driver.c



On Tue, Apr 27, 2010 at 06:45:16PM +0200, Jim Meyering wrote:
> I ran clang on the very latest and it spotted this problem:
> >From qemu_driver.c, around line 11100,
> 
>     else {
>         /* qemu is a little funny with running guests and the restoration
>          * of snapshots.  If the snapshot was taken online,
>          * then after a "loadvm" monitor command, the VM is set running
>          * again.  If the snapshot was taken offline, then after a "loadvm"
>          * monitor command the VM is left paused.  Unpausing it leads to
>          * the memory state *before* the loadvm with the disk *after* the
>          * loadvm, which obviously is bound to corrupt something.
>          * Therefore we destroy the domain and set it to "off" in this case.
>          */
> 
>         if (virDomainObjIsActive(vm)) {
>             qemudShutdownVMDaemon(driver, vm);
>             event = virDomainEventNewFromObj(vm,
>                                              VIR_DOMAIN_EVENT_STOPPED,
>                                              VIR_DOMAIN_EVENT_STOPPED_FROM_SNAPSHOT);
>             if (!vm->persistent) {
>                 if (qemuDomainObjEndJob(vm) > 0)
>                     virDomainRemoveInactive(&driver->domains, vm);
>                 vm = NULL;

This needs to add 'goto endjob' or possibly 'goto cleanup'

>             }
>         }
> 
>         if (qemuDomainSnapshotSetActive(vm, driver->snapshotDir) < 0)
>             goto endjob;
>     }
> 
>     vm->state = snap->def->state;
> 
>     ret = 0;
> 
> endjob:
>     if (vm && qemuDomainObjEndJob(vm) == 0)
>         vm = NULL;
> 
> Note how "vm" is set to NULL.
> Then, it can be dereferenced both via qemuDomainSnapshotSetActive
> and via the vm->state = ... assignment.

Daniel
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