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, 122 insertions, 0 deletions

diff --git a/drivers/mfd/rt5120.c b/drivers/mfd/rt5120.c
new file mode 100644
index 000000000..a229eb292
--- /dev/null
+++ b/drivers/mfd/rt5120.c
@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Richtek Technology Corp.
+ * Author: ChiYuan Huang <cy_huang@richtek.com>
+ */
+
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#define RT5120_REG_INTENABLE	0x1D
+#define RT5120_REG_INTSTAT	0x1E
+#define RT5120_REG_FZCMODE	0x44
+
+#define RT5120_INT_HOTDIE	0
+#define RT5120_INT_PWRKEY_REL	5
+#define RT5120_INT_PWRKEY_PRESS	6
+
+static const struct regmap_range rt5120_rd_yes_ranges[] = {
+	regmap_reg_range(0x03, 0x13),
+	regmap_reg_range(0x1c, 0x20),
+	regmap_reg_range(0x44, 0x44),
+};
+
+static const struct regmap_range rt5120_wr_yes_ranges[] = {
+	regmap_reg_range(0x06, 0x13),
+	regmap_reg_range(0x1c, 0x20),
+	regmap_reg_range(0x44, 0x44),
+};
+
+static const struct regmap_access_table rt5120_rd_table = {
+	.yes_ranges = rt5120_rd_yes_ranges,
+	.n_yes_ranges = ARRAY_SIZE(rt5120_rd_yes_ranges),
+};
+
+static const struct regmap_access_table rt5120_wr_table = {
+	.yes_ranges = rt5120_wr_yes_ranges,
+	.n_yes_ranges = ARRAY_SIZE(rt5120_wr_yes_ranges),
+};
+
+static const struct regmap_config rt5120_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = RT5120_REG_FZCMODE,
+
+	.wr_table = &rt5120_wr_table,
+	.rd_table = &rt5120_rd_table,
+};
+
+static const struct regmap_irq rt5120_irqs[] = {
+	REGMAP_IRQ_REG_LINE(RT5120_INT_HOTDIE, 8),
+	REGMAP_IRQ_REG_LINE(RT5120_INT_PWRKEY_REL, 8),
+	REGMAP_IRQ_REG_LINE(RT5120_INT_PWRKEY_PRESS, 8),
+};
+
+static const struct regmap_irq_chip rt5120_irq_chip = {
+	.name = "rt5120-pmic",
+	.status_base = RT5120_REG_INTSTAT,
+	.unmask_base = RT5120_REG_INTENABLE,
+	.ack_base = RT5120_REG_INTSTAT,
+	.use_ack = true,
+	.num_regs = 1,
+	.irqs = rt5120_irqs,
+	.num_irqs = ARRAY_SIZE(rt5120_irqs),
+};
+
+static const struct resource rt5120_regulator_resources[] = {
+	DEFINE_RES_IRQ(RT5120_INT_HOTDIE),
+};
+
+static const struct resource rt5120_pwrkey_resources[] = {
+	DEFINE_RES_IRQ_NAMED(RT5120_INT_PWRKEY_PRESS, "pwrkey-press"),
+	DEFINE_RES_IRQ_NAMED(RT5120_INT_PWRKEY_REL, "pwrkey-release"),
+};
+
+static const struct mfd_cell rt5120_devs[] = {
+	MFD_CELL_RES("rt5120-regulator", rt5120_regulator_resources),
+	MFD_CELL_OF("rt5120-pwrkey", rt5120_pwrkey_resources, NULL, 0, 0, "richtek,rt5120-pwrkey"),
+};
+
+static int rt5120_probe(struct i2c_client *i2c)
+{
+	struct device *dev = &i2c->dev;
+	struct regmap *regmap;
+	struct regmap_irq_chip_data *irq_data;
+	int ret;
+
+	regmap = devm_regmap_init_i2c(i2c, &rt5120_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(dev, PTR_ERR(regmap),
+				     "Failed to init regmap\n");
+
+	ret = devm_regmap_add_irq_chip(dev, regmap, i2c->irq, IRQF_ONESHOT, 0,
+				       &rt5120_irq_chip, &irq_data);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to add IRQ chip\n");
+
+	return devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO, rt5120_devs,
+				    ARRAY_SIZE(rt5120_devs), NULL, 0,
+				    regmap_irq_get_domain(irq_data));
+}
+
+static const struct of_device_id rt5120_device_match_table[] = {
+	{ .compatible = "richtek,rt5120" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rt5120_device_match_table);
+
+static struct i2c_driver rt5120_driver = {
+	.driver = {
+		.name = "rt5120",
+		.of_match_table = rt5120_device_match_table,
+	},
+	.probe = rt5120_probe,
+};
+module_i2c_driver(rt5120_driver);
+
+MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
+MODULE_DESCRIPTION("Richtek RT5120 I2C driver");
+MODULE_LICENSE("GPL v2");