Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions).
As found with Coccinelle[1], add __counted_by for struct f_midi. Additionally, since the element count member must be set before accessing the annotated flexible array member, move its initialization earlier. [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> Cc: John Keeping <j...@keeping.me.uk> Cc: Peter Chen <peter.c...@nxp.com> Cc: Hulk Robot <hul...@huawei.com> Cc: Allen Pais <allen.l...@gmail.com> Cc: Will McVicker <willmcvic...@google.com> Cc: Davidlohr Bueso <d...@stgolabs.net> Cc: Zhang Qilong <zhangqilo...@huawei.com> Cc: linux-...@vger.kernel.org Signed-off-by: Kees Cook <keesc...@chromium.org> --- drivers/usb/gadget/function/f_midi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c index 2d02f25f9597..033e347554db 100644 --- a/drivers/usb/gadget/function/f_midi.c +++ b/drivers/usb/gadget/function/f_midi.c @@ -99,7 +99,7 @@ struct f_midi { unsigned int in_last_port; unsigned char free_ref; - struct gmidi_in_port in_ports_array[/* in_ports */]; + struct gmidi_in_port in_ports_array[] __counted_by(in_ports); }; static inline struct f_midi *func_to_midi(struct usb_function *f) @@ -1349,6 +1349,7 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi) status = -ENOMEM; goto setup_fail; } + midi->in_ports = opts->in_ports; for (i = 0; i < opts->in_ports; i++) midi->in_ports_array[i].cable = i; @@ -1359,7 +1360,6 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi) status = -ENOMEM; goto midi_free; } - midi->in_ports = opts->in_ports; midi->out_ports = opts->out_ports; midi->index = opts->index; midi->buflen = opts->buflen; -- 2.34.1
