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, 153 insertions, 0 deletions

diff --git a/drivers/input/misc/qnap-mcu-input.c b/drivers/input/misc/qnap-mcu-input.c
new file mode 100644
index 000000000..3be899bfc
--- /dev/null
+++ b/drivers/input/misc/qnap-mcu-input.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Driver for input events on QNAP-MCUs
+ *
+ * Copyright (C) 2024 Heiko Stuebner <heiko@sntech.de>
+ */
+
+#include <linux/input.h>
+#include <linux/mfd/qnap-mcu.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <uapi/linux/input-event-codes.h>
+
+/*
+ * The power-key needs to be pressed for a while to create an event,
+ * so there is no use for overly frequent polling.
+ */
+#define POLL_INTERVAL		500
+
+struct qnap_mcu_input_dev {
+	struct input_dev *input;
+	struct qnap_mcu *mcu;
+	struct device *dev;
+
+	struct work_struct beep_work;
+	int beep_type;
+};
+
+static void qnap_mcu_input_poll(struct input_dev *input)
+{
+	struct qnap_mcu_input_dev *idev = input_get_drvdata(input);
+	static const u8 cmd[] = { '@', 'C', 'V' };
+	u8 reply[4];
+	int state, ret;
+
+	/* poll the power button */
+	ret = qnap_mcu_exec(idev->mcu, cmd, sizeof(cmd), reply, sizeof(reply));
+	if (ret)
+		return;
+
+	/* First bytes must mirror the sent command */
+	if (memcmp(cmd, reply, sizeof(cmd))) {
+		dev_err(idev->dev, "malformed data received\n");
+		return;
+	}
+
+	state = reply[3] - 0x30;
+	input_event(input, EV_KEY, KEY_POWER, state);
+	input_sync(input);
+}
+
+static void qnap_mcu_input_beeper_work(struct work_struct *work)
+{
+	struct qnap_mcu_input_dev *idev =
+		container_of(work, struct qnap_mcu_input_dev, beep_work);
+	const u8 cmd[] = { '@', 'C', (idev->beep_type == SND_TONE) ? '3' : '2' };
+
+	qnap_mcu_exec_with_ack(idev->mcu, cmd, sizeof(cmd));
+}
+
+static int qnap_mcu_input_event(struct input_dev *input, unsigned int type,
+				unsigned int code, int value)
+{
+	struct qnap_mcu_input_dev *idev = input_get_drvdata(input);
+
+	if (type != EV_SND || (code != SND_BELL && code != SND_TONE))
+		return -EOPNOTSUPP;
+
+	if (value < 0)
+		return -EINVAL;
+
+	/* beep runtime is determined by the MCU */
+	if (value == 0)
+		return 0;
+
+	/* Schedule work to actually turn the beeper on */
+	idev->beep_type = code;
+	schedule_work(&idev->beep_work);
+
+	return 0;
+}
+
+static void qnap_mcu_input_close(struct input_dev *input)
+{
+	struct qnap_mcu_input_dev *idev = input_get_drvdata(input);
+
+	cancel_work_sync(&idev->beep_work);
+}
+
+static int qnap_mcu_input_probe(struct platform_device *pdev)
+{
+	struct qnap_mcu *mcu = dev_get_drvdata(pdev->dev.parent);
+	struct qnap_mcu_input_dev *idev;
+	struct device *dev = &pdev->dev;
+	struct input_dev *input;
+	int ret;
+
+	idev = devm_kzalloc(dev, sizeof(*idev), GFP_KERNEL);
+	if (!idev)
+		return -ENOMEM;
+
+	input = devm_input_allocate_device(dev);
+	if (!input)
+		return -ENOMEM;
+
+	idev->input = input;
+	idev->dev = dev;
+	idev->mcu = mcu;
+
+	input_set_drvdata(input, idev);
+
+	input->name		= "qnap-mcu";
+	input->phys		= "qnap-mcu-input/input0";
+	input->id.bustype	= BUS_HOST;
+	input->id.vendor	= 0x0001;
+	input->id.product	= 0x0001;
+	input->id.version	= 0x0100;
+	input->event		= qnap_mcu_input_event;
+	input->close		= qnap_mcu_input_close;
+
+	input_set_capability(input, EV_KEY, KEY_POWER);
+	input_set_capability(input, EV_SND, SND_BELL);
+	input_set_capability(input, EV_SND, SND_TONE);
+
+	INIT_WORK(&idev->beep_work, qnap_mcu_input_beeper_work);
+
+	ret = input_setup_polling(input, qnap_mcu_input_poll);
+	if (ret)
+		return dev_err_probe(dev, ret, "unable to set up polling\n");
+
+	input_set_poll_interval(input, POLL_INTERVAL);
+
+	ret = input_register_device(input);
+	if (ret)
+		return dev_err_probe(dev, ret, "unable to register input device\n");
+
+	return 0;
+}
+
+static struct platform_driver qnap_mcu_input_driver = {
+	.probe = qnap_mcu_input_probe,
+	.driver = {
+		.name = "qnap-mcu-input",
+	},
+};
+module_platform_driver(qnap_mcu_input_driver);
+
+MODULE_ALIAS("platform:qnap-mcu-input");
+MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
+MODULE_DESCRIPTION("QNAP MCU input driver");
+MODULE_LICENSE("GPL");