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, 98 insertions, 0 deletions

diff --git a/drivers/input/misc/88pm886-onkey.c b/drivers/input/misc/88pm886-onkey.c
new file mode 100644
index 000000000..284ff5190
--- /dev/null
+++ b/drivers/input/misc/88pm886-onkey.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/88pm886.h>
+
+struct pm886_onkey {
+	struct input_dev *idev;
+	struct pm886_chip *chip;
+};
+
+static irqreturn_t pm886_onkey_irq_handler(int irq, void *data)
+{
+	struct pm886_onkey *onkey = data;
+	struct regmap *regmap = onkey->chip->regmap;
+	struct input_dev *idev = onkey->idev;
+	struct device *parent = idev->dev.parent;
+	unsigned int val;
+	int err;
+
+	err = regmap_read(regmap, PM886_REG_STATUS1, &val);
+	if (err) {
+		dev_err(parent, "Failed to read status: %d\n", err);
+		return IRQ_NONE;
+	}
+	val &= PM886_ONKEY_STS1;
+
+	input_report_key(idev, KEY_POWER, val);
+	input_sync(idev);
+
+	return IRQ_HANDLED;
+}
+
+static int pm886_onkey_probe(struct platform_device *pdev)
+{
+	struct pm886_chip *chip = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	struct pm886_onkey *onkey;
+	struct input_dev *idev;
+	int irq, err;
+
+	onkey = devm_kzalloc(dev, sizeof(*onkey), GFP_KERNEL);
+	if (!onkey)
+		return -ENOMEM;
+
+	onkey->chip = chip;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return dev_err_probe(dev, irq, "Failed to get IRQ\n");
+
+	idev = devm_input_allocate_device(dev);
+	if (!idev) {
+		dev_err(dev, "Failed to allocate input device\n");
+		return -ENOMEM;
+	}
+	onkey->idev = idev;
+
+	idev->name = "88pm886-onkey";
+	idev->phys = "88pm886-onkey/input0";
+	idev->id.bustype = BUS_I2C;
+
+	input_set_capability(idev, EV_KEY, KEY_POWER);
+
+	err = devm_request_threaded_irq(dev, irq, NULL, pm886_onkey_irq_handler,
+					IRQF_ONESHOT | IRQF_NO_SUSPEND, "onkey",
+					onkey);
+	if (err)
+		return dev_err_probe(dev, err, "Failed to request IRQ\n");
+
+	err = input_register_device(idev);
+	if (err)
+		return dev_err_probe(dev, err, "Failed to register input device\n");
+
+	return 0;
+}
+
+static const struct platform_device_id pm886_onkey_id_table[] = {
+	{ "88pm886-onkey", },
+	{ }
+};
+MODULE_DEVICE_TABLE(platform, pm886_onkey_id_table);
+
+static struct platform_driver pm886_onkey_driver = {
+	.driver = {
+		.name = "88pm886-onkey",
+	},
+	.probe = pm886_onkey_probe,
+	.id_table = pm886_onkey_id_table,
+};
+module_platform_driver(pm886_onkey_driver);
+
+MODULE_DESCRIPTION("Marvell 88PM886 onkey driver");
+MODULE_AUTHOR("Karel Balej <balejk@matfyz.cz>");
+MODULE_LICENSE("GPL");