Re: [PATCH] hw/core: define stack variable to NULL to fix qtest with sanitizers

[Philippe Mathieu-Daudé]

(Cc'ing QAPI maintainer)

On 24/11/23 02:53, Daniel Hoffman wrote:
> This was the only failure preventing `make check` from passing with sanitizers
> enabled on my configuration.

IIUC this is due to visit_start_list() which expects a NULL list,
see qapi/qapi-visit-core.c:

bool visit_start_list(Visitor *v, const char *name, GenericList **list,
                      size_t size, Error **errp)
{
    bool ok;

    assert(!list || size >= sizeof(GenericList));

which is well defined in its declaration:

/*
 * Start visiting a list.
 *
 * @name expresses the relationship of this list to its parent
 * container; see the general description of @name above.
 *
 * @list must be non-NULL for a real walk, in which case @size
 * determines how much memory an input or clone visitor will allocate
 * into *@list (at least sizeof(GenericList)).  Some visitors also
 * allow @list to be NULL for a virtual walk, in which case @size is
 * ignored.
 ...

With the patch description improved:
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

> Signed-off-by: Daniel Hoffman <dhoff749@gmail.com>
> ---
>   hw/core/qdev-properties.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
> index 91632f7be9f..4caa78b7bc5 100644
> --- a/hw/core/qdev-properties.c
> +++ b/hw/core/qdev-properties.c
> @@ -690,7 +690,7 @@ static void get_prop_array(Object *obj, Visitor *v, const 
> char *name,
>       uint32_t *alenptr = object_field_prop_ptr(obj, prop);
>       void **arrayptr = (void *)obj + prop->arrayoffset;
>       char *elem = *arrayptr;
> -    GenericList *list;
> +    GenericList *list = NULL;
>       const size_t list_elem_size = sizeof(*list) + prop->arrayfieldsize;
>       int i;
>       bool ok;