Replace the fake VLA at end of the vbva_mouse_pointer_shape shape with
a real VLA to fix a "memcpy: detected field-spanning write error" warning:
[ 13.319813] memcpy: detected field-spanning write (size 16896) of single field "p->data" at drivers/gpu/drm/vboxvideo/hgsmi_base.c:154 (size 4)
[ 13.319841] WARNING: CPU: 0 PID: 1105 at drivers/gpu/drm/vboxvideo/hgsmi_base.c:154 hgsmi_update_pointer_shape+0x192/0x1c0 [vboxvideo]
[ 13.320038] Call Trace:
[ 13.320173] hgsmi_update_pointer_shape [vboxvideo]
[ 13.320184] vbox_cursor_atomic_update [vboxvideo]
Note as mentioned in the added comment it seems the original length
calculation for the allocated and send hgsmi buffer is 4 bytes too large.
Changing this is not the goal of this patch, so this behavior is kept.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/gpu/drm/vboxvideo/hgsmi_base.c | 10 +++++++++-
drivers/gpu/drm/vboxvideo/vboxvideo.h | 4 +---
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/vboxvideo/hgsmi_base.c b/drivers/gpu/drm/vboxvideo/hgsmi_base.c
index 8c041d7ce4f1..87dccaecc3e5 100644
--- a/drivers/gpu/drm/vboxvideo/hgsmi_base.c
+++ b/drivers/gpu/drm/vboxvideo/hgsmi_base.c
@@ -139,7 +139,15 @@ int hgsmi_update_pointer_shape(struct gen_pool *ctx, u32 flags,
flags |= VBOX_MOUSE_POINTER_VISIBLE;
}
- p = hgsmi_buffer_alloc(ctx, sizeof(*p) + pixel_len, HGSMI_CH_VBVA,
+ /*
+ * The 4 extra bytes come from switching struct vbva_mouse_pointer_shape
+ * from having a 4 bytes fixed array at the end to using a proper VLA
+ * at the end. These 4 extra bytes were not subtracted from sizeof(*p)
+ * before the switch to the VLA, so this way the behavior is unchanged.
+ * Chances are these 4 extra bytes are not necessary but they are kept
+ * to avoid regressions.
+ */
+ p = hgsmi_buffer_alloc(ctx, sizeof(*p) + pixel_len + 4, HGSMI_CH_VBVA,
VBVA_MOUSE_POINTER_SHAPE);
if (!p)
return -ENOMEM;
diff --git a/drivers/gpu/drm/vboxvideo/vboxvideo.h b/drivers/gpu/drm/vboxvideo/vboxvideo.h
index f60d82504da0..79ec8481de0e 100644
--- a/drivers/gpu/drm/vboxvideo/vboxvideo.h
+++ b/drivers/gpu/drm/vboxvideo/vboxvideo.h
@@ -351,10 +351,8 @@ struct vbva_mouse_pointer_shape {
* Bytes in the gap between the AND and the XOR mask are undefined.
* XOR mask scanlines have no gap between them and size of XOR mask is:
* xor_len = width * 4 * height.
- *
- * Preallocate 4 bytes for accessing actual data as p->data.
*/
- u8 data[4];
+ u8 data[];
} __packed;
/* pointer is visible */
--
2.44.0
