On Thu, Feb 20, 2020 at 07:20:17AM -0600, Gustavo A. R. Silva wrote:
> The current codebase makes use of the zero-length array language
> extension to the C90 standard, but the preferred mechanism to declare
> variable-length types such as these ones is a flexible array member[1][2],
> introduced in C99:
>
> struct foo {
> int stuff;
> struct boo array[];
> };
>
> By making use of the mechanism above, we will get a compiler warning
> in case the flexible array does not occur last in the structure, which
> will help us prevent some kind of undefined behavior bugs from being
> inadvertently introduced[3] to the codebase from now on.
>
> Also, notice that, dynamic memory allocations won't be affected by
> this change:
>
> "Flexible array members have incomplete type, and so the sizeof operator
> may not be applied. As a quirk of the original implementation of
> zero-length arrays, sizeof evaluates to zero."[1]
>
> This issue was found with the help of Coccinelle.
>
> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> [2] https://github.com/KSPP/linux/issues/21
> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> ---
> drivers/usb/atm/usbatm.h | 2 +-
> drivers/usb/dwc2/hcd.h | 2 +-
> drivers/usb/host/ehci-tegra.c | 2 +-
> drivers/usb/host/ehci.h | 4 ++--
> drivers/usb/host/fotg210.h | 2 +-
> drivers/usb/host/ohci.h | 4 ++--
> drivers/usb/host/xhci-mtk.h | 2 +-
> drivers/usb/host/xhci.h | 4 ++--
> drivers/usb/serial/io_usbvend.h | 4 ++--
> drivers/usb/serial/ti_usb_3410_5052.c | 4 ++--
> include/linux/usb.h | 4 ++--
> include/linux/usb/audio-v2.h | 2 +-
> include/linux/usb/audio-v3.h | 2 +-
> include/linux/usb/gadget.h | 2 +-
> include/linux/usb/hcd.h | 2 +-
> include/linux/usbdevice_fs.h | 2 +-
> 16 files changed, 22 insertions(+), 22 deletions(-)
Looks like your scripts still doesn't catch every instance. A simple
grep like
git grep -A1 '\[0\];$' drivers/usb/ | grep -B1 '}'
found at least three more in
drivers/usb/atm/ueagle-atm.c
drivers/usb/gadget/function/f_phonet.c
drivers/usb/musb/musb_host.c
Johan
