Trigger NEON alignment fault

graphene-align.c

#include <glib.h>
#include <glib-object.h>
#include <graphene.h>
#include <stdio.h>

G_BEGIN_DECLS

#define GST_TYPE_GRAPHENE_ALIGN            (graphene_align_get_type())
#define GRAPHENE_ALIGN(obj)            (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_GRAPHENE_ALIGN,GrapheneAlign))
#define GST_IS_GRAPHENE_ALIGN(obj)         (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_GRAPHENE_ALIGN))
#define GRAPHENE_ALIGN_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST((klass) ,GST_TYPE_GRAPHENE_ALIGN,GrapheneAlignClass))
#define GST_IS_GRAPHENE_ALIGN_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE((klass) ,GST_TYPE_GRAPHENE_ALIGN))
#define GRAPHENE_ALIGN_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS((obj) ,GST_TYPE_GRAPHENE_ALIGN,GrapheneAlignClass))

typedef struct _GrapheneAlign GrapheneAlign;
typedef struct _GrapheneAlignClass GrapheneAlignClass;

struct _GrapheneAlign
{
  GObject parent;

  // Simulate a bunch of other fields
  char padding[64];

  graphene_vec3_t aligned_vector;
};

struct _GrapheneAlignClass
{
  GObjectClass filter_class;
};

GType graphene_align_get_type (void);

G_END_DECLS

#define graphene_align_parent_class parent_class

G_DEFINE_TYPE (GrapheneAlign, graphene_align,
	       G_TYPE_OBJECT);

static void
graphene_align_class_init (GrapheneAlignClass * klass) {

}

static void
graphene_align_init (GrapheneAlign * align)
{
  printf("Pointer to instance is %p, alignment is %#0x\n", align, G_ALIGNOF(GrapheneAlign));
  graphene_vec3_init(&align->aligned_vector, 0., 0., 0.);
}

int main(int argc, char **argv) {
  unsigned pad = 0;
  GrapheneAlign *align;

  printf("Offset of graphene vector: %#0x\n", offsetof(GrapheneAlign, aligned_vector));
  if (argc > 1) {
    pad = atoi(argv[1]);
  }
  if (pad > 0) {
    printf("Allocating %u padding bytes\n", pad);
    g_slice_alloc(pad);
  } else {
    printf("No padding bytes allocated\n");
  }

  align = g_object_new(graphene_align_get_type(), NULL);
  g_object_unref(align);
  return 0;
}

Sample Makefile:

CFLAGS = -Wall

PKGCONFIG_DEPS = graphene-1.0 gobject-2.0

CFLAGS += $(shell pkg-config --cflags $(PKGCONFIG_DEPS))
LDFLAGS += $(shell pkg-config --libs-only-L $(PKGCONFIG_DEPS))
LDLIBS += $(shell pkg-config --libs-only-l $(PKGCONFIG_DEPS))

graphene-align: graphene-align.o

Sample invocation:

./graphene-align 0 # Doesn't crash
./graphene-align 1024 # Doesn't crash
./graphene-align 16 # Crashes reliably on Cortex-A9