Re: [PATCH 0/4] tree-wide: fix comparison to bitshift when dealing with a mask

Julia Lawall
2018-02-06T14:08:35Z

On Tue, 6 Feb 2018, Dan Carpenter wrote:

> That found 4 that I think Wolfram's grep missed.
>
> arch/um/drivers/vector_user.h | 2 --
> drivers/gpu/drm/mxsfb/mxsfb_regs.h | 2 --
> drivers/video/fbdev/mxsfb.c | 2 --
> include/drm/drm_scdc_helper.h | 3 ---
>
> But it didn't find the two bugs that Geert found where the right side
> wasn't a number literal.
>
> drivers/net/can/m_can/m_can.c:#define RXFC_FWM_MASK (0x7f < RXFC_FWM_SHIFT)

OK, I can easily add this in - I've got rules to protect against reporting
it at the moment. It may end up with false positives.

> drivers/usb/gadget/udc/goku_udc.h:#define INT_EPnNAK(n) (0x00100 < (n)) /* 0 < n < 4 */

This is indeed harder, because one has to look at the usage site.

julia