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, 159 insertions, 0 deletions

diff --git a/drivers/mfd/88pm80x.c b/drivers/mfd/88pm80x.c
new file mode 100644
index 000000000..bbc1a87f0
--- /dev/null
+++ b/drivers/mfd/88pm80x.c
@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * I2C driver for Marvell 88PM80x
+ *
+ * Copyright (C) 2012 Marvell International Ltd.
+ * Haojian Zhuang <haojian.zhuang@marvell.com>
+ * Joseph(Yossi) Hanin <yhanin@marvell.com>
+ * Qiao Zhou <zhouqiao@marvell.com>
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/mfd/88pm80x.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/err.h>
+
+/* 88pm80x chips have same definition for chip id register. */
+#define PM80X_CHIP_ID			(0x00)
+#define PM80X_CHIP_ID_NUM(x)		(((x) >> 5) & 0x7)
+#define PM80X_CHIP_ID_REVISION(x)	((x) & 0x1F)
+
+struct pm80x_chip_mapping {
+	unsigned int	id;
+	int		type;
+};
+
+static struct pm80x_chip_mapping chip_mapping[] = {
+	/* 88PM800 chip id number */
+	{0x3,	CHIP_PM800},
+	/* 88PM805 chip id number */
+	{0x0,	CHIP_PM805},
+	/* 88PM860 chip id number */
+	{0x4,	CHIP_PM860},
+};
+
+/*
+ * workaround: some registers needed by pm805 are defined in pm800, so
+ * need to use this global variable to maintain the relation between
+ * pm800 and pm805. would remove it after HW chip fixes the issue.
+ */
+static struct pm80x_chip *g_pm80x_chip;
+
+const struct regmap_config pm80x_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+EXPORT_SYMBOL_GPL(pm80x_regmap_config);
+
+
+int pm80x_init(struct i2c_client *client)
+{
+	struct pm80x_chip *chip;
+	struct regmap *map;
+	unsigned int val;
+	int i, ret = 0;
+
+	chip =
+	    devm_kzalloc(&client->dev, sizeof(struct pm80x_chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	map = devm_regmap_init_i2c(client, &pm80x_regmap_config);
+	if (IS_ERR(map)) {
+		ret = PTR_ERR(map);
+		dev_err(&client->dev, "Failed to allocate register map: %d\n",
+			ret);
+		return ret;
+	}
+
+	chip->client = client;
+	chip->regmap = map;
+
+	chip->irq = client->irq;
+
+	chip->dev = &client->dev;
+	i2c_set_clientdata(chip->client, chip);
+
+	ret = regmap_read(chip->regmap, PM80X_CHIP_ID, &val);
+	if (ret < 0) {
+		dev_err(chip->dev, "Failed to read CHIP ID: %d\n", ret);
+		return ret;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(chip_mapping); i++) {
+		if (chip_mapping[i].id == PM80X_CHIP_ID_NUM(val)) {
+			chip->type = chip_mapping[i].type;
+			break;
+		}
+	}
+
+	if (i == ARRAY_SIZE(chip_mapping)) {
+		dev_err(chip->dev,
+			"Failed to detect Marvell 88PM800:ChipID[0x%x]\n", val);
+		return -EINVAL;
+	}
+
+	device_init_wakeup(&client->dev, 1);
+
+	/*
+	 * workaround: set g_pm80x_chip to the first probed chip. if the
+	 * second chip is probed, just point to the companion to each
+	 * other so that pm805 can access those specific register. would
+	 * remove it after HW chip fixes the issue.
+	 */
+	if (!g_pm80x_chip)
+		g_pm80x_chip = chip;
+	else {
+		chip->companion = g_pm80x_chip->client;
+		g_pm80x_chip->companion = chip->client;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pm80x_init);
+
+int pm80x_deinit(void)
+{
+	/*
+	 * workaround: clear the dependency between pm800 and pm805.
+	 * would remove it after HW chip fixes the issue.
+	 */
+	if (g_pm80x_chip->companion)
+		g_pm80x_chip->companion = NULL;
+	else
+		g_pm80x_chip = NULL;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pm80x_deinit);
+
+static int pm80x_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct pm80x_chip *chip = i2c_get_clientdata(client);
+
+	if (chip && chip->wu_flag)
+		if (device_may_wakeup(chip->dev))
+			enable_irq_wake(chip->irq);
+
+	return 0;
+}
+
+static int pm80x_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct pm80x_chip *chip = i2c_get_clientdata(client);
+
+	if (chip && chip->wu_flag)
+		if (device_may_wakeup(chip->dev))
+			disable_irq_wake(chip->irq);
+
+	return 0;
+}
+
+EXPORT_GPL_SIMPLE_DEV_PM_OPS(pm80x_pm_ops, pm80x_suspend, pm80x_resume);
+
+MODULE_DESCRIPTION("I2C Driver for Marvell 88PM80x");
+MODULE_AUTHOR("Qiao Zhou <zhouqiao@marvell.com>");
+MODULE_LICENSE("GPL");