[libvirt] [PATCH] qemu: avoid dereferencing a NULL pointer

[Eric Blake]

On 09/16/2011 10:17 AM, ajia at redhat.com wrote:
> From: Alex Jia<ajia at redhat.com>
>
> * src/qemu/qemu_migration.c: avoid dereferencing a pointer that might be
>    null "vmdef" when calling virDomainSaveConfig.

Thanks for catching this.

>
> Signed-off-by: Alex Jia<ajia at redhat.com>
> ---
>   src/qemu/qemu_migration.c |    3 ++-
>   1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index d9f8d93..69ced88 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
> @@ -2510,7 +2510,8 @@ qemuMigrationFinish(struct qemud_driver *driver,
>               if (vm->persistent)
>                   newVM = 0;
>               vm->persistent = 1;
> -            vmdef = virDomainObjGetPersistentDef(driver->caps, vm);
> +            if (!(vmdef = virDomainObjGetPersistentDef(driver->caps, vm)))
> +                goto endjob;
>               if (virDomainSaveConfig(driver->configDir, vmdef)<  0) {
>                   /* Hmpf.  Migration was successful, but making it persistent

But your fix is not quite right.  I think we need something like:

if (!(vmdef = virDomainObjGetPersistentDef(driver->caps, vm)) ||
     virDomainSaveConfig(driver->configDir, vmdef) < 0) {
     /* Hmpf. ... */

I'll let Dan weigh in on it, too.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org