We should not be leaving half-mapped usages with potentially invalid keycodes, as that may confuse hidinput_find_key() when the key is located by index, which may end up feeding way too large keycode into the VT keyboard handler and cause OOB write there: 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: https://syzkaller.appspot.com/bug?extid=19340dff067c2d3835c0 Reported-by: syzbot+19340dff067c2d3835c0@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> --- I'll be putting a guard into drivers/tty/vt/keyboard.c as well. Please consider for stable. drivers/hid/hid-input.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c index 63855f275a38..3957d1c4d967 100644 --- a/drivers/hid/hid-input.c +++ b/drivers/hid/hid-input.c @@ -1215,9 +1215,11 @@ static void hidinput_configure_usage(struct hid_input *hidinput, struct hid_fiel set_bit(MSC_SCAN, input->mscbit); } -ignore: return; +ignore: + usage->type = 0; + usage->code = 0; } static void hidinput_handle_scroll(struct hid_usage *usage, -- 2.24.0.432.g9d3f5f5b63-goog -- Dmitry
