On Mon, Oct 09, 2023 at 03:48:19PM +0200, 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.
Yes, good call.
>
> 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>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
-Kees
> ---
> include/net/bluetooth/bluetooth.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
> index 7ffa8c192c3f2..27ee1bf51c235 100644
> --- a/include/net/bluetooth/bluetooth.h
> +++ b/include/net/bluetooth/bluetooth.h
> @@ -359,11 +359,11 @@ static inline bool bdaddr_type_is_le(u8 type)
> #define BDADDR_NONE (&(bdaddr_t) {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}})
>
> /* Copy, swap, convert BD Address */
> -static inline int bacmp(const bdaddr_t *ba1, const bdaddr_t *ba2)
> +static __always_inline int bacmp(const bdaddr_t *ba1, const bdaddr_t *ba2)
> {
> return memcmp(ba1, ba2, sizeof(bdaddr_t));
> }
> -static inline void bacpy(bdaddr_t *dst, const bdaddr_t *src)
> +static __always_inline void bacpy(bdaddr_t *dst, const bdaddr_t *src)
> {
> memcpy(dst, src, sizeof(bdaddr_t));
> }
> --
> 2.39.2
>
--
Kees Cook
