Re: [PATCH] Bluetooth: mark bacmp() and bacpy() as __always_inline

[Kees Cook]

On Mon, Oct 09, 2023 at 05:36:55PM +0200, Arnd Bergmann wrote:
> On Mon, Oct 9, 2023, at 15:48, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@xxxxxxxx>
> >
> > These functions are simple wrappers around memcmp() and memcpy(), which
> > contain compile-time checks for buffer overflow. Something in gcc-13 and
> > likely other versions makes this trigger a warning when the functions
> > are not inlined and the compiler misunderstands the buffer length:
> >
> > In file included from net/bluetooth/hci_event.c:32:
> > In function 'bacmp',
> >     inlined from 'hci_conn_request_evt' at 
> > net/bluetooth/hci_event.c:3276:7:
> > include/net/bluetooth/bluetooth.h:364:16: error: 'memcmp' specified 
> > bound 6 exceeds source size 0 [-Werror=stringop-overread]
> >   364 |         return memcmp(ba1, ba2, sizeof(bdaddr_t));
> >       |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > Use the __always_inline annotation to ensure that the helpers are
> > correctly checked. This has no effect on the actual correctness
> > of the code, but avoids the warning. Since the patch that introduced
> > the warning is marked for stable backports, this one should also
> > go that way to avoid introducing build regressions.
> >
> > Fixes: d70e44fef8621 ("Bluetooth: Reject connection with the device 
> > which has same BD_ADDR")
> > Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> > Cc: Lee, Chun-Yi <jlee@xxxxxxxx>
> > Cc: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
> > Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> 
> Sorry, I have to retract this, something went wrong on my
> testing and I now see the same problem in some configs regardless
> of whether the patch is applied or not.

Perhaps turn them into macros instead?

-- 
Kees Cook