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, 102 insertions, 0 deletions

diff --git a/drivers/net/phy/et1011c.c b/drivers/net/phy/et1011c.c
new file mode 100644
index 000000000..6cd8d7758
--- /dev/null
+++ b/drivers/net/phy/et1011c.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * drivers/net/phy/et1011c.c
+ *
+ * Driver for LSI ET1011C PHYs
+ *
+ * Author: Chaithrika U S
+ *
+ * Copyright (c) 2008 Texas Instruments
+ */
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/unistd.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/mii.h>
+#include <linux/ethtool.h>
+#include <linux/phy.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <asm/irq.h>
+
+#define ET1011C_STATUS_REG	(0x1A)
+#define ET1011C_CONFIG_REG	(0x16)
+#define ET1011C_SPEED_MASK		(0x0300)
+#define ET1011C_GIGABIT_SPEED		(0x0200)
+#define ET1011C_TX_FIFO_MASK		(0x3000)
+#define ET1011C_TX_FIFO_DEPTH_8		(0x0000)
+#define ET1011C_TX_FIFO_DEPTH_16	(0x1000)
+#define ET1011C_INTERFACE_MASK		(0x0007)
+#define ET1011C_GMII_INTERFACE		(0x0002)
+#define ET1011C_SYS_CLK_EN		(0x01 << 4)
+
+
+MODULE_DESCRIPTION("LSI ET1011C PHY driver");
+MODULE_AUTHOR("Chaithrika U S");
+MODULE_LICENSE("GPL");
+
+static int et1011c_config_aneg(struct phy_device *phydev)
+{
+	int ctl = phy_read(phydev, MII_BMCR);
+
+	if (ctl < 0)
+		return ctl;
+	ctl &= ~(BMCR_FULLDPLX | BMCR_SPEED100 | BMCR_SPEED1000 |
+		 BMCR_ANENABLE);
+	/* First clear the PHY */
+	phy_write(phydev, MII_BMCR, ctl | BMCR_RESET);
+
+	return genphy_config_aneg(phydev);
+}
+
+static int et1011c_read_status(struct phy_device *phydev)
+{
+	static int speed;
+	int ret;
+	u32 val;
+
+	ret = genphy_read_status(phydev);
+
+	if (speed != phydev->speed) {
+		speed = phydev->speed;
+		val = phy_read(phydev, ET1011C_STATUS_REG);
+		if ((val & ET1011C_SPEED_MASK) ==
+					ET1011C_GIGABIT_SPEED) {
+			val = phy_read(phydev, ET1011C_CONFIG_REG);
+			val &= ~ET1011C_TX_FIFO_MASK;
+			phy_write(phydev, ET1011C_CONFIG_REG, val |
+					  ET1011C_GMII_INTERFACE |
+					  ET1011C_SYS_CLK_EN |
+					  ET1011C_TX_FIFO_DEPTH_16);
+
+		}
+	}
+	return ret;
+}
+
+static struct phy_driver et1011c_driver[] = { {
+	.phy_id		= 0x0282f014,
+	.name		= "ET1011C",
+	.phy_id_mask	= 0xfffffff0,
+	/* PHY_GBIT_FEATURES */
+	.config_aneg	= et1011c_config_aneg,
+	.read_status	= et1011c_read_status,
+} };
+
+module_phy_driver(et1011c_driver);
+
+static const struct mdio_device_id __maybe_unused et1011c_tbl[] = {
+	{ 0x0282f014, 0xfffffff0 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, et1011c_tbl);