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, 130 insertions, 0 deletions

diff --git a/drivers/input/misc/ab8500-ponkey.c b/drivers/input/misc/ab8500-ponkey.c
new file mode 100644
index 000000000..a9b901368
--- /dev/null
+++ b/drivers/input/misc/ab8500-ponkey.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ *
+ * Author: Sundar Iyer <sundar.iyer@stericsson.com> for ST-Ericsson
+ *
+ * AB8500 Power-On Key handler
+ */
+
+#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/mfd/abx500/ab8500.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+/**
+ * struct ab8500_ponkey - ab8500 ponkey information
+ * @idev: pointer to input device
+ * @ab8500: ab8500 parent
+ * @irq_dbf: irq number for falling transition
+ * @irq_dbr: irq number for rising transition
+ */
+struct ab8500_ponkey {
+	struct input_dev	*idev;
+	struct ab8500		*ab8500;
+	int			irq_dbf;
+	int			irq_dbr;
+};
+
+/* AB8500 gives us an interrupt when ONKEY is held */
+static irqreturn_t ab8500_ponkey_handler(int irq, void *data)
+{
+	struct ab8500_ponkey *ponkey = data;
+
+	if (irq == ponkey->irq_dbf)
+		input_report_key(ponkey->idev, KEY_POWER, true);
+	else if (irq == ponkey->irq_dbr)
+		input_report_key(ponkey->idev, KEY_POWER, false);
+
+	input_sync(ponkey->idev);
+
+	return IRQ_HANDLED;
+}
+
+static int ab8500_ponkey_probe(struct platform_device *pdev)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(pdev->dev.parent);
+	struct ab8500_ponkey *ponkey;
+	struct input_dev *input;
+	int irq_dbf, irq_dbr;
+	int error;
+
+	irq_dbf = platform_get_irq_byname(pdev, "ONKEY_DBF");
+	if (irq_dbf < 0)
+		return irq_dbf;
+
+	irq_dbr = platform_get_irq_byname(pdev, "ONKEY_DBR");
+	if (irq_dbr < 0)
+		return irq_dbr;
+
+	ponkey = devm_kzalloc(&pdev->dev, sizeof(struct ab8500_ponkey),
+			      GFP_KERNEL);
+	if (!ponkey)
+		return -ENOMEM;
+
+	input = devm_input_allocate_device(&pdev->dev);
+	if (!input)
+		return -ENOMEM;
+
+	ponkey->idev = input;
+	ponkey->ab8500 = ab8500;
+	ponkey->irq_dbf = irq_dbf;
+	ponkey->irq_dbr = irq_dbr;
+
+	input->name = "AB8500 POn(PowerOn) Key";
+	input->dev.parent = &pdev->dev;
+
+	input_set_capability(input, EV_KEY, KEY_POWER);
+
+	error = devm_request_any_context_irq(&pdev->dev, ponkey->irq_dbf,
+					     ab8500_ponkey_handler, 0,
+					     "ab8500-ponkey-dbf", ponkey);
+	if (error < 0) {
+		dev_err(ab8500->dev, "Failed to request dbf IRQ#%d: %d\n",
+			ponkey->irq_dbf, error);
+		return error;
+	}
+
+	error = devm_request_any_context_irq(&pdev->dev, ponkey->irq_dbr,
+					     ab8500_ponkey_handler, 0,
+					     "ab8500-ponkey-dbr", ponkey);
+	if (error < 0) {
+		dev_err(ab8500->dev, "Failed to request dbr IRQ#%d: %d\n",
+			ponkey->irq_dbr, error);
+		return error;
+	}
+
+	error = input_register_device(ponkey->idev);
+	if (error) {
+		dev_err(ab8500->dev, "Can't register input device: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id ab8500_ponkey_match[] = {
+	{ .compatible = "stericsson,ab8500-ponkey", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ab8500_ponkey_match);
+#endif
+
+static struct platform_driver ab8500_ponkey_driver = {
+	.driver		= {
+		.name	= "ab8500-poweron-key",
+		.of_match_table = of_match_ptr(ab8500_ponkey_match),
+	},
+	.probe		= ab8500_ponkey_probe,
+};
+module_platform_driver(ab8500_ponkey_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Sundar Iyer <sundar.iyer@stericsson.com>");
+MODULE_DESCRIPTION("ST-Ericsson AB8500 Power-ON(Pon) Key driver");