linux-kernel - [PATCH 5.3 066/105] tty: vt: keyboard: reject invalid keycodes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20191211150247.684002354@linuxfoundation.org>
Date:   Wed, 11 Dec 2019 16:05:55 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+19340dff067c2d3835c0@...kaller.appspotmail.com,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: [PATCH 5.3 066/105] tty: vt: keyboard: reject invalid keycodes

From: Dmitry Torokhov <dmitry.torokhov@...il.com>

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@...kaller.appspotmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: stable <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20191122204220.GA129459@dtor-ws
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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);