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, 163 insertions, 0 deletions

diff --git a/drivers/usb/misc/usb4604.c b/drivers/usb/misc/usb4604.c
new file mode 100644
index 000000000..2ae965671
--- /dev/null
+++ b/drivers/usb/misc/usb4604.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for SMSC USB4604 USB HSIC 4-port 2.0 hub controller driver
+ * Based on usb3503 driver
+ *
+ * Copyright (c) 2012-2013 Dongjin Kim (tobetter@gmail.com)
+ * Copyright (c) 2016 Linaro Ltd.
+ */
+
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/gpio/consumer.h>
+
+enum usb4604_mode {
+	USB4604_MODE_UNKNOWN,
+	USB4604_MODE_HUB,
+	USB4604_MODE_STANDBY,
+};
+
+struct usb4604 {
+	enum usb4604_mode	mode;
+	struct device		*dev;
+	struct gpio_desc	*gpio_reset;
+};
+
+static void usb4604_reset(struct usb4604 *hub, int state)
+{
+	gpiod_set_value_cansleep(hub->gpio_reset, state);
+
+	/* Wait for i2c logic to come up */
+	if (state)
+		msleep(250);
+}
+
+static int usb4604_connect(struct usb4604 *hub)
+{
+	struct device *dev = hub->dev;
+	struct i2c_client *client = to_i2c_client(dev);
+	int err;
+	u8 connect_cmd[] = { 0xaa, 0x55, 0x00 };
+
+	usb4604_reset(hub, 1);
+
+	err = i2c_master_send(client, connect_cmd, ARRAY_SIZE(connect_cmd));
+	if (err < 0) {
+		usb4604_reset(hub, 0);
+		return err;
+	}
+
+	hub->mode = USB4604_MODE_HUB;
+	dev_dbg(dev, "switched to HUB mode\n");
+
+	return 0;
+}
+
+static int usb4604_switch_mode(struct usb4604 *hub, enum usb4604_mode mode)
+{
+	struct device *dev = hub->dev;
+	int err = 0;
+
+	switch (mode) {
+	case USB4604_MODE_HUB:
+		err = usb4604_connect(hub);
+		break;
+
+	case USB4604_MODE_STANDBY:
+		usb4604_reset(hub, 0);
+		dev_dbg(dev, "switched to STANDBY mode\n");
+		break;
+
+	default:
+		dev_err(dev, "unknown mode is requested\n");
+		err = -EINVAL;
+		break;
+	}
+
+	return err;
+}
+
+static int usb4604_probe(struct usb4604 *hub)
+{
+	struct device *dev = hub->dev;
+	struct device_node *np = dev->of_node;
+	struct gpio_desc *gpio;
+	u32 mode = USB4604_MODE_HUB;
+
+	gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(gpio))
+		return PTR_ERR(gpio);
+	hub->gpio_reset = gpio;
+
+	if (of_property_read_u32(np, "initial-mode", &hub->mode))
+		hub->mode = mode;
+
+	return usb4604_switch_mode(hub, hub->mode);
+}
+
+static int usb4604_i2c_probe(struct i2c_client *i2c)
+{
+	struct usb4604 *hub;
+
+	hub = devm_kzalloc(&i2c->dev, sizeof(*hub), GFP_KERNEL);
+	if (!hub)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, hub);
+	hub->dev = &i2c->dev;
+
+	return usb4604_probe(hub);
+}
+
+static int __maybe_unused usb4604_i2c_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct usb4604 *hub = i2c_get_clientdata(client);
+
+	usb4604_switch_mode(hub, USB4604_MODE_STANDBY);
+
+	return 0;
+}
+
+static int __maybe_unused usb4604_i2c_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct usb4604 *hub = i2c_get_clientdata(client);
+
+	usb4604_switch_mode(hub, hub->mode);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(usb4604_i2c_pm_ops, usb4604_i2c_suspend,
+		usb4604_i2c_resume);
+
+static const struct i2c_device_id usb4604_id[] = {
+	{ .name = "usb4604" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, usb4604_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id usb4604_of_match[] = {
+	{ .compatible = "smsc,usb4604" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, usb4604_of_match);
+#endif
+
+static struct i2c_driver usb4604_i2c_driver = {
+	.driver = {
+		.name = "usb4604",
+		.pm = pm_ptr(&usb4604_i2c_pm_ops),
+		.of_match_table = of_match_ptr(usb4604_of_match),
+	},
+	.probe		= usb4604_i2c_probe,
+	.id_table	= usb4604_id,
+};
+module_i2c_driver(usb4604_i2c_driver);
+
+MODULE_DESCRIPTION("USB4604 USB HUB driver");
+MODULE_LICENSE("GPL v2");