[Spice-devel] [spice-gtk v1] gstaudio: fix ci due potential null pointer dereference

[Frediano Ziglio]

> 
> From: Victor Toso <me at victortoso.com>
> 
> Can't happen as GstElement *e is not NULL but doing extra G_OBJECT(e) cast
> guarantees this for compiler.
> 
>  > spice-gstaudio.c: In function ‘playback_volume_changed’:
>  > /usr/include/glib-2.0/gobject/gtype.h:2280:70: error: potential null
>  > pointer dereference [-Werror=null-dereference]
>  >  #define _G_TYPE_IGC(ip, gt, ct)         ((ct*) (((GTypeInstance*)
>  >  ip)->g_class))
>  >                                                 ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~
>  > /usr/include/glib-2.0/gobject/gtype.h:525:66: note: in expansion of macro
>  > ‘_G_TYPE_IGC’
>  >  #define G_TYPE_INSTANCE_GET_CLASS(instance, g_type, c_type)
>  >  (_G_TYPE_IGC ((instance), (g_type), c_type))
>  >                                                                   ^~~~~~~~~~~
>  > /usr/include/glib-2.0/gobject/gobject.h:86:38: note: in expansion of macro
>  > ‘G_TYPE_INSTANCE_GET_CLASS’
>  >  #define G_OBJECT_GET_CLASS(object)  (G_TYPE_INSTANCE_GET_CLASS ((object),
>  >  G_TYPE_OBJECT, GObjectClass))
>  >                                       ^~~~~~~~~~~~~~~~~~~~~~~~~
>  > spice-gstaudio.c:373:45: note: in expansion of macro ‘G_OBJECT_GET_CLASS’
>  >      } else if (g_object_class_find_property(G_OBJECT_GET_CLASS (e),
>  >      "volume") != NULL) {
>                                                  ^~~~~~~~~~~~~~~~~~
> 
> Signed-off-by: Victor Toso <victortoso at redhat.com>

Why not adding g_return_if_fail(e != NULL) before using "e" instead ?

> ---
> 
>  Working CI:
>  https://gitlab.freedesktop.org/victortoso/spice-gtk/pipelines/15885
> 
>  src/spice-gstaudio.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/src/spice-gstaudio.c b/src/spice-gstaudio.c
> index 51ff028..b2d9cd3 100644
> --- a/src/spice-gstaudio.c
> +++ b/src/spice-gstaudio.c
> @@ -370,7 +370,7 @@ static void playback_volume_changed(GObject *object,
> GParamSpec *pspec, gpointer
>  
>      if (GST_IS_STREAM_VOLUME(e)) {
>          gst_stream_volume_set_volume(GST_STREAM_VOLUME(e),
>          GST_STREAM_VOLUME_FORMAT_CUBIC, vol);
> -    } else if (g_object_class_find_property(G_OBJECT_GET_CLASS (e),
> "volume") != NULL) {
> +    } else if (g_object_class_find_property(G_OBJECT_GET_CLASS(G_OBJECT(e)),
> "volume") != NULL) {
>          g_object_set(e, "volume", vol, NULL);
>      } else {
>          g_warning("playback: ignoring volume change on %s",
>          gst_element_get_name(e));
> @@ -399,7 +399,7 @@ static void playback_mute_changed(GObject *object,
> GParamSpec *pspec, gpointer d
>  
>      if (GST_IS_STREAM_VOLUME(e)) {
>          gst_stream_volume_set_mute(GST_STREAM_VOLUME(e), mute);
> -    } else if (g_object_class_find_property(G_OBJECT_GET_CLASS (e), "mute")
> != NULL) {
> +    } else if (g_object_class_find_property(G_OBJECT_GET_CLASS(G_OBJECT(e)),
> "mute") != NULL) {
>          g_object_set(e, "mute", mute, NULL);
>      } else {
>          g_warning("playback: ignoring mute change on %s",
>          gst_element_get_name(e));
> @@ -437,7 +437,7 @@ static void record_volume_changed(GObject *object,
> GParamSpec *pspec, gpointer d
>  
>      if (GST_IS_STREAM_VOLUME(e)) {
>          gst_stream_volume_set_volume(GST_STREAM_VOLUME(e),
>          GST_STREAM_VOLUME_FORMAT_CUBIC, vol);
> -    } else if (g_object_class_find_property(G_OBJECT_GET_CLASS (e),
> "volume") != NULL) {
> +    } else if (g_object_class_find_property(G_OBJECT_GET_CLASS(G_OBJECT(e)),
> "volume") != NULL) {
>          g_object_set(e, "volume", vol, NULL);
>      } else {
>          g_warning("record: ignoring volume change on %s",
>          gst_element_get_name(e));
> @@ -466,7 +466,7 @@ static void record_mute_changed(GObject *object,
> GParamSpec *pspec, gpointer dat
>  
>      if (GST_IS_STREAM_VOLUME (e)) {
>          gst_stream_volume_set_mute(GST_STREAM_VOLUME(e), mute);
> -    } else if (g_object_class_find_property(G_OBJECT_GET_CLASS (e), "mute")
> != NULL) {
> +    } else if (g_object_class_find_property(G_OBJECT_GET_CLASS(G_OBJECT(e)),
> "mute") != NULL) {
>          g_object_set(e, "mute", mute, NULL);
>      } else {
>          g_warning("record: ignoring mute change on %s",
>          gst_element_get_name(e));

Frediano