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, 150 insertions, 0 deletions

diff --git a/drivers/input/misc/tps65219-pwrbutton.c b/drivers/input/misc/tps65219-pwrbutton.c
new file mode 100644
index 000000000..7a58bae4f
--- /dev/null
+++ b/drivers/input/misc/tps65219-pwrbutton.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Driver for TPS65219 Push Button
+//
+// Copyright (C) 2022 BayLibre Incorporated - https://www.baylibre.com/
+
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/tps65219.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+struct tps65219_pwrbutton {
+	struct device *dev;
+	struct input_dev *idev;
+	char phys[32];
+};
+
+static irqreturn_t tps65219_pb_push_irq(int irq, void *_pwr)
+{
+	struct tps65219_pwrbutton *pwr = _pwr;
+
+	input_report_key(pwr->idev, KEY_POWER, 1);
+	pm_wakeup_event(pwr->dev, 0);
+	input_sync(pwr->idev);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t tps65219_pb_release_irq(int irq, void *_pwr)
+{
+	struct tps65219_pwrbutton *pwr = _pwr;
+
+	input_report_key(pwr->idev, KEY_POWER, 0);
+	input_sync(pwr->idev);
+
+	return IRQ_HANDLED;
+}
+
+static int tps65219_pb_probe(struct platform_device *pdev)
+{
+	struct tps65219 *tps = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	struct tps65219_pwrbutton *pwr;
+	struct input_dev *idev;
+	int error;
+	int push_irq;
+	int release_irq;
+
+	pwr = devm_kzalloc(dev, sizeof(*pwr), GFP_KERNEL);
+	if (!pwr)
+		return -ENOMEM;
+
+	idev = devm_input_allocate_device(dev);
+	if (!idev)
+		return -ENOMEM;
+
+	idev->name = pdev->name;
+	snprintf(pwr->phys, sizeof(pwr->phys), "%s/input0",
+		 pdev->name);
+	idev->phys = pwr->phys;
+	idev->id.bustype = BUS_I2C;
+
+	input_set_capability(idev, EV_KEY, KEY_POWER);
+
+	pwr->dev = dev;
+	pwr->idev = idev;
+	device_init_wakeup(dev, true);
+
+	push_irq = platform_get_irq(pdev, 0);
+	if (push_irq < 0)
+		return -EINVAL;
+
+	release_irq = platform_get_irq(pdev, 1);
+	if (release_irq < 0)
+		return -EINVAL;
+
+	error = devm_request_threaded_irq(dev, push_irq, NULL,
+					  tps65219_pb_push_irq,
+					  IRQF_ONESHOT,
+					  dev->init_name, pwr);
+	if (error) {
+		dev_err(dev, "failed to request push IRQ #%d: %d\n", push_irq,
+			error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(dev, release_irq, NULL,
+					  tps65219_pb_release_irq,
+					  IRQF_ONESHOT,
+					  dev->init_name, pwr);
+	if (error) {
+		dev_err(dev, "failed to request release IRQ #%d: %d\n",
+			release_irq, error);
+		return error;
+	}
+
+	error = input_register_device(idev);
+	if (error) {
+		dev_err(dev, "Can't register power button: %d\n", error);
+		return error;
+	}
+
+	/* Enable interrupts for the pushbutton */
+	regmap_clear_bits(tps->regmap, TPS65219_REG_MASK_CONFIG,
+			  TPS65219_REG_MASK_INT_FOR_PB_MASK);
+
+	/* Set PB/EN/VSENSE pin to be a pushbutton */
+	regmap_update_bits(tps->regmap, TPS65219_REG_MFP_2_CONFIG,
+			   TPS65219_MFP_2_EN_PB_VSENSE_MASK, TPS65219_MFP_2_PB);
+
+	return 0;
+}
+
+static void tps65219_pb_remove(struct platform_device *pdev)
+{
+	struct tps65219 *tps = dev_get_drvdata(pdev->dev.parent);
+	int ret;
+
+	/* Disable interrupt for the pushbutton */
+	ret = regmap_set_bits(tps->regmap, TPS65219_REG_MASK_CONFIG,
+			      TPS65219_REG_MASK_INT_FOR_PB_MASK);
+	if (ret)
+		dev_warn(&pdev->dev, "Failed to disable irq (%pe)\n", ERR_PTR(ret));
+}
+
+static const struct platform_device_id tps65219_pwrbtn_id_table[] = {
+	{ "tps65219-pwrbutton", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, tps65219_pwrbtn_id_table);
+
+static struct platform_driver tps65219_pb_driver = {
+	.probe = tps65219_pb_probe,
+	.remove = tps65219_pb_remove,
+	.driver = {
+		.name = "tps65219_pwrbutton",
+	},
+	.id_table = tps65219_pwrbtn_id_table,
+};
+module_platform_driver(tps65219_pb_driver);
+
+MODULE_DESCRIPTION("TPS65219 Power Button");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Markus Schneider-Pargmann <msp@baylibre.com");