Re: [Qemu-devel] [PATCH] qapi: output visitor crashes qemu if it encounters a NULL value

[Eric Blake <eblake@redhat.com>]

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On 02/17/2014 04:52 AM, Marcel Apfelbaum wrote:
> A NULL value is not added to visitor's stack, but there
> is no check for that when the visitor tries to return
> that value, leading to Qemu crash.

Do you have an easy formula for reproducing the crash?

> 
> Signed-off-by: Marcel Apfelbaum <marcel.a@redhat.com>
> ---
>  qapi/qmp-output-visitor.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
> index 74a5684..0562f49 100644
> --- a/qapi/qmp-output-visitor.c
> +++ b/qapi/qmp-output-visitor.c
> @@ -66,6 +66,11 @@ static QObject *qmp_output_pop(QmpOutputVisitor *qov)
>  static QObject *qmp_output_first(QmpOutputVisitor *qov)
>  {
>      QStackEntry *e = QTAILQ_LAST(&qov->stack, QStack);
> +
> +    if (!e) {
> +        return NULL;
> +    }
> +

The code looks okay to me, but without a formula, my review is fairly weak:

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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