From: Hans de Goede <hdegoede@xxxxxxxxxx> [ Upstream commit d92b90f9a54d9300a6e883258e79f36dab53bfae ] 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> Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20240827104523.17442-1-hdegoede@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@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 8c041d7ce4f1b..87dccaecc3e57 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 f60d82504da02..79ec8481de0e4 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 */ -- 2.43.0
