drm/crtc: add sanity checks to create_dumb()
Lets make sure some basic expressions are always true:
bpp != NULL
width != NULL
height != NULL
stride = bpp * width < 2^32
size = stride * height < 2^32
PAGE_ALIGN(size) < 2^32
At least the udl driver doesn't check for multiplication-overflows, so
lets just make sure it will never happen. These checks allow drivers to do
any 32bit math without having to test for mult-overflows themselves.
The two divisions might hurt performance a bit, but dumb_create() is only
used for scanout-buffers, so that should be fine. We could use 64bit math
to avoid the divisions, but that may be slow on 32bit machines.. Or maybe
there should just be a "safe_mult32()" helper, which currently doesn't
exist (I think?).
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
1 file changed