linux/drivers/hid/hid-emsff.c
Alan Stern d9d4b1e46d HID: Fix assumption that devices have inputs
The syzbot fuzzer found a slab-out-of-bounds write bug in the hid-gaff
driver.  The problem is caused by the driver's assumption that the
device must have an input report.  While this will be true for all
normal HID input devices, a suitably malicious device can violate the
assumption.

The same assumption is present in over a dozen other HID drivers.
This patch fixes them by checking that the list of hid_inputs for the
hid_device is nonempty before allowing it to be used.

Reported-and-tested-by: syzbot+403741a091bf41d4ae79@syzkaller.appspotmail.com
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: <stable@vger.kernel.org>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
2019-10-03 15:36:40 -04:00

149 lines
3.2 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Force feedback support for EMS Trio Linker Plus II
*
* Copyright (c) 2010 Ignaz Forster <ignaz.forster@gmx.de>
*/
/*
*/
#include <linux/hid.h>
#include <linux/input.h>
#include <linux/module.h>
#include "hid-ids.h"
struct emsff_device {
struct hid_report *report;
};
static int emsff_play(struct input_dev *dev, void *data,
struct ff_effect *effect)
{
struct hid_device *hid = input_get_drvdata(dev);
struct emsff_device *emsff = data;
int weak, strong;
weak = effect->u.rumble.weak_magnitude;
strong = effect->u.rumble.strong_magnitude;
dbg_hid("called with 0x%04x 0x%04x\n", strong, weak);
weak = weak * 0xff / 0xffff;
strong = strong * 0xff / 0xffff;
emsff->report->field[0]->value[1] = weak;
emsff->report->field[0]->value[2] = strong;
dbg_hid("running with 0x%02x 0x%02x\n", strong, weak);
hid_hw_request(hid, emsff->report, HID_REQ_SET_REPORT);
return 0;
}
static int emsff_init(struct hid_device *hid)
{
struct emsff_device *emsff;
struct hid_report *report;
struct hid_input *hidinput;
struct list_head *report_list =
&hid->report_enum[HID_OUTPUT_REPORT].report_list;
struct input_dev *dev;
int error;
if (list_empty(&hid->inputs)) {
hid_err(hid, "no inputs found\n");
return -ENODEV;
}
hidinput = list_first_entry(&hid->inputs, struct hid_input, list);
dev = hidinput->input;
if (list_empty(report_list)) {
hid_err(hid, "no output reports found\n");
return -ENODEV;
}
report = list_first_entry(report_list, struct hid_report, list);
if (report->maxfield < 1) {
hid_err(hid, "no fields in the report\n");
return -ENODEV;
}
if (report->field[0]->report_count < 7) {
hid_err(hid, "not enough values in the field\n");
return -ENODEV;
}
emsff = kzalloc(sizeof(struct emsff_device), GFP_KERNEL);
if (!emsff)
return -ENOMEM;
set_bit(FF_RUMBLE, dev->ffbit);
error = input_ff_create_memless(dev, emsff, emsff_play);
if (error) {
kfree(emsff);
return error;
}
emsff->report = report;
emsff->report->field[0]->value[0] = 0x01;
emsff->report->field[0]->value[1] = 0x00;
emsff->report->field[0]->value[2] = 0x00;
emsff->report->field[0]->value[3] = 0x00;
emsff->report->field[0]->value[4] = 0x00;
emsff->report->field[0]->value[5] = 0x00;
emsff->report->field[0]->value[6] = 0x00;
hid_hw_request(hid, emsff->report, HID_REQ_SET_REPORT);
hid_info(hid, "force feedback for EMS based devices by Ignaz Forster <ignaz.forster@gmx.de>\n");
return 0;
}
static int ems_probe(struct hid_device *hdev, const struct hid_device_id *id)
{
int ret;
ret = hid_parse(hdev);
if (ret) {
hid_err(hdev, "parse failed\n");
goto err;
}
ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
if (ret) {
hid_err(hdev, "hw start failed\n");
goto err;
}
ret = emsff_init(hdev);
if (ret) {
dev_err(&hdev->dev, "force feedback init failed\n");
hid_hw_stop(hdev);
goto err;
}
return 0;
err:
return ret;
}
static const struct hid_device_id ems_devices[] = {
{ HID_USB_DEVICE(USB_VENDOR_ID_EMS, USB_DEVICE_ID_EMS_TRIO_LINKER_PLUS_II) },
{ }
};
MODULE_DEVICE_TABLE(hid, ems_devices);
static struct hid_driver ems_driver = {
.name = "hkems",
.id_table = ems_devices,
.probe = ems_probe,
};
module_hid_driver(ems_driver);
MODULE_LICENSE("GPL");