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, 135 insertions, 0 deletions

diff --git a/drivers/input/misc/e3x0-button.c b/drivers/input/misc/e3x0-button.c
new file mode 100644
index 000000000..5bd527117
--- /dev/null
+++ b/drivers/input/misc/e3x0-button.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014, National Instruments Corp. All rights reserved.
+ *
+ * Driver for NI Ettus Research USRP E3x0 Button Driver
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+static irqreturn_t e3x0_button_release_handler(int irq, void *data)
+{
+	struct input_dev *idev = data;
+
+	input_report_key(idev, KEY_POWER, 0);
+	input_sync(idev);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t e3x0_button_press_handler(int irq, void *data)
+{
+	struct input_dev *idev = data;
+
+	input_report_key(idev, KEY_POWER, 1);
+	pm_wakeup_event(idev->dev.parent, 0);
+	input_sync(idev);
+
+	return IRQ_HANDLED;
+}
+
+static int e3x0_button_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(platform_get_irq_byname(pdev, "press"));
+
+	return 0;
+}
+
+static int e3x0_button_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(platform_get_irq_byname(pdev, "press"));
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(e3x0_button_pm_ops,
+				e3x0_button_suspend, e3x0_button_resume);
+
+static int e3x0_button_probe(struct platform_device *pdev)
+{
+	struct input_dev *input;
+	int irq_press, irq_release;
+	int error;
+
+	irq_press = platform_get_irq_byname(pdev, "press");
+	if (irq_press < 0)
+		return irq_press;
+
+	irq_release = platform_get_irq_byname(pdev, "release");
+	if (irq_release < 0)
+		return irq_release;
+
+	input = devm_input_allocate_device(&pdev->dev);
+	if (!input)
+		return -ENOMEM;
+
+	input->name = "NI Ettus Research USRP E3x0 Button Driver";
+	input->phys = "e3x0_button/input0";
+	input->dev.parent = &pdev->dev;
+
+	input_set_capability(input, EV_KEY, KEY_POWER);
+
+	error = devm_request_irq(&pdev->dev, irq_press,
+				 e3x0_button_press_handler, 0,
+				 "e3x0-button", input);
+	if (error) {
+		dev_err(&pdev->dev, "Failed to request 'press' IRQ#%d: %d\n",
+			irq_press, error);
+		return error;
+	}
+
+	error = devm_request_irq(&pdev->dev, irq_release,
+				 e3x0_button_release_handler, 0,
+				 "e3x0-button", input);
+	if (error) {
+		dev_err(&pdev->dev, "Failed to request 'release' IRQ#%d: %d\n",
+			irq_release, error);
+		return error;
+	}
+
+	error = input_register_device(input);
+	if (error) {
+		dev_err(&pdev->dev, "Can't register input device: %d\n", error);
+		return error;
+	}
+
+	device_init_wakeup(&pdev->dev, 1);
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id e3x0_button_match[] = {
+	{ .compatible = "ettus,e3x0-button", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, e3x0_button_match);
+#endif
+
+static struct platform_driver e3x0_button_driver = {
+	.driver		= {
+		.name	= "e3x0-button",
+		.of_match_table = of_match_ptr(e3x0_button_match),
+		.pm	= pm_sleep_ptr(&e3x0_button_pm_ops),
+	},
+	.probe		= e3x0_button_probe,
+};
+
+module_platform_driver(e3x0_button_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Moritz Fischer <moritz.fischer@ettus.com>");
+MODULE_DESCRIPTION("NI Ettus Research USRP E3x0 Button driver");
+MODULE_ALIAS("platform:e3x0-button");