HID: hid-input: clear unmapped usages

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]

Cc: stable@vger.kernel.org
Reported-by: syzbot+19340dff067c2d3835c0@syzkaller.appspotmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Tested-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 63855f275a38c3f39eaa917744909a2ec97b9c8f..dea9cc65bf8007bc101c26b308c28e32b7714abb 100644 (file)
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -1132,9 +1132,15 @@ static void hidinput_configure_usage(struct hid_input *hidinput, struct hid_fiel
        }
 
 mapped:
-       if (device->driver->input_mapped && device->driver->input_mapped(device,
-                               hidinput, field, usage, &bit, &max) < 0)
-               goto ignore;
+       if (device->driver->input_mapped &&
+           device->driver->input_mapped(device, hidinput, field, usage,
+                                        &bit, &max) < 0) {
+               /*
+                * The driver indicated that no further generic handling
+                * of the usage is desired.
+                */
+               return;
+       }
 
        set_bit(usage->type, input->evbit);
 
@@ -1215,9 +1221,11 @@ mapped:
                set_bit(MSC_SCAN, input->mscbit);
        }
 
-ignore:
        return;
 
+ignore:
+       usage->type = 0;
+       usage->code = 0;
 }
 
 static void hidinput_handle_scroll(struct hid_usage *usage,