Re: [Qemu-devel] [PATCH] json-parser: Fix potential NULL pointer segfault

[Luiz Capitulino <lcapitulino@redhat.com>]

On Mon,  3 Sep 2012 21:19:11 +0200
Stefan Weil <sw@weilnetz.de> wrote:

> Report from smatch:
> json-parser.c:474 parse_object(62) error: potential null derefence 'dict'.
> json-parser.c:553 parse_array(75) error: potential null derefence 'list'.
> 
> Label 'out' in json-parser.c can be called with list == NULL
> which is passed to QDECREF.
> 
> Modify QDECREF to handle a NULL argument (inline function qobject_decref
> already handles them, too).
> 
> Signed-off-by: Stefan Weil <sw@weilnetz.de>

Applied to qmp-next branch, thanks!

> ---
> 
> I did not change QINCREF because there are currently no errors caused
> by that rarely used macro.
> 
> This patch can be used instead of the previous patch which fixed
> the problem directly in json-parser.c
> (see http://patchwork.ozlabs.org/patch/181129/).
> 
> Regards,
> Stefan Weil
> 
>  qobject.h |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/qobject.h b/qobject.h
> index d42386d..9124649 100644
> --- a/qobject.h
> +++ b/qobject.h
> @@ -71,7 +71,7 @@ typedef struct QObject {
>  
>  /* High-level interface for qobject_decref() */
>  #define QDECREF(obj)              \
> -    qobject_decref(QOBJECT(obj))
> +    qobject_decref(obj ? QOBJECT(obj) : NULL)
>  
>  /* Initialize an object to default values */
>  #define QOBJECT_INIT(obj, qtype_type)   \