Re: [PATCH] machine: do not crash if default RAM backend name has been stollen

[Igor Mammedov]

On Mon, 22 May 2023 15:17:17 +0200
Igor Mammedov <imammedo@redhat.com> wrote:

Paolo,
can you pick it up?

> QEMU aborts when default RAM backend should be used (i.e. no
> explicit '-machine memory-backend=' specified) but user
> has created an object which 'id' equals to default RAM backend
> name used by board.
> 
>  $QEMU -machine pc \
>        -object memory-backend-ram,id=pc.ram,size=4294967296
> 
>  Actual results:
>  QEMU 7.2.0 monitor - type 'help' for more information
>  (qemu) Unexpected error in object_property_try_add() at ../qom/object.c:1239:
>  qemu-kvm: attempt to add duplicate property 'pc.ram' to object (type 
> 'container')
>  Aborted (core dumped)
> 
> Instead of abort, check for the conflicting 'id' and exit with
> an error, suggesting how to remedy the issue.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> CC: thuth@redhat.com
> ---
>  hw/core/machine.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 07f763eb2e..1000406211 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -1338,6 +1338,14 @@ void machine_run_board_init(MachineState *machine, 
> const char *mem_path, Error *
>          }
>      } else if (machine_class->default_ram_id && machine->ram_size &&
>                 numa_uses_legacy_mem()) {
> +        if (object_property_find(object_get_objects_root(),
> +                                 machine_class->default_ram_id)) {
> +            error_setg(errp, "object name '%s' is reserved for the default"
> +                " RAM backend, it can't be used for any other purposes."
> +                " Change the object's 'id' to something else",
> +                machine_class->default_ram_id);
> +            return;
> +        }
>          if (!create_default_memdev(current_machine, mem_path, errp)) {
>              return;
>          }