From: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> commit b2b2dd71e0859436d4e05b2f61f86140250ed3f8 upstream. Do not try to handle keycodes that are too big, otherwise we risk doing out-of-bounds writes: BUG: KASAN: global-out-of-bounds in clear_bit include/asm-generic/bitops-instrumented.h:56 [inline] BUG: KASAN: global-out-of-bounds in kbd_keycode drivers/tty/vt/keyboard.c:1411 [inline] BUG: KASAN: global-out-of-bounds in kbd_event+0xe6b/0x3790 drivers/tty/vt/keyboard.c:1495 Write of size 8 at addr ffffffff89a1b2d8 by task syz-executor108/1722 ... kbd_keycode drivers/tty/vt/keyboard.c:1411 [inline] kbd_event+0xe6b/0x3790 drivers/tty/vt/keyboard.c:1495 input_to_handler+0x3b6/0x4c0 drivers/input/input.c:118 input_pass_values.part.0+0x2e3/0x720 drivers/input/input.c:145 input_pass_values drivers/input/input.c:949 [inline] input_set_keycode+0x290/0x320 drivers/input/input.c:954 evdev_handle_set_keycode_v2+0xc4/0x120 drivers/input/evdev.c:882 evdev_do_ioctl drivers/input/evdev.c:1150 [inline] In this case we were dealing with a fuzzed HID device that declared over 12K buttons, and while HID layer should not be reporting to us such big keycodes, we should also be defensive and reject invalid data ourselves as well. Reported-by: syzbot+19340dff067c2d3835c0@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> Cc: stable <stable@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20191122204220.GA129459@dtor-ws Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/tty/vt/keyboard.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/tty/vt/keyboard.c +++ b/drivers/tty/vt/keyboard.c @@ -1491,7 +1491,7 @@ static void kbd_event(struct input_handl if (event_type == EV_MSC && event_code == MSC_RAW && HW_RAW(handle->dev)) kbd_rawcode(value); - if (event_type == EV_KEY) + if (event_type == EV_KEY && event_code <= KEY_MAX) kbd_keycode(event_code, value, HW_RAW(handle->dev)); spin_unlock(&kbd_event_lock);
