openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 149 insertions, 0 deletions

diff --git a/drivers/hid/hid-emsff.c b/drivers/hid/hid-emsff.c
new file mode 100644
index 000000000..1b4ad18f6
--- /dev/null
+++ b/drivers/hid/hid-emsff.c
@@ -0,0 +1,149 @@
+// 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_obj(struct emsff_device);
+	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_DESCRIPTION("Force feedback support for EMS Trio Linker Plus II");
+MODULE_LICENSE("GPL");
+