Messages in this thread | | | Date | Mon, 9 Oct 2023 13:43:12 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] [v2] Bluetooth: avoid memcmp() out of bounds warning |
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On Mon, Oct 09, 2023 at 10:31:31PM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > bacmp() is a wrapper around memcpy(), which contain compile-time > checks for buffer overflow. Since the hci_conn_request_evt() also calls > bt_dev_dbg() with an implicit NULL pointer check, the compiler is now > aware of a case where 'hdev' is NULL and treats this as meaning that > zero bytes are available: > > 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)); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Add another NULL pointer check before the bacmp() to ensure the compiler > understands the code flow enough to not warn about it. 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@chromium.org> > Cc: "Lee, Chun-Yi" <jlee@suse.com> > Cc: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> > Cc: Marcel Holtmann <marcel@holtmann.org> > Cc: stable@vger.kernel.org > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
A weird side-effect of the NULL check, but not unreasonable. :)
Reviewed-by: Kees Cook <keescook@chromium.org>
-- Kees Cook
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