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, 163 insertions, 0 deletions

diff --git a/drivers/net/phy/qsemi.c b/drivers/net/phy/qsemi.c
new file mode 100644
index 000000000..7b70ba6ca
--- /dev/null
+++ b/drivers/net/phy/qsemi.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * drivers/net/phy/qsemi.c
+ *
+ * Driver for Quality Semiconductor PHYs
+ *
+ * Author: Andy Fleming
+ *
+ * Copyright (c) 2004 Freescale Semiconductor, Inc.
+ */
+#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 <asm/io.h>
+#include <asm/irq.h>
+#include <linux/uaccess.h>
+
+/* ------------------------------------------------------------------------- */
+/* The Quality Semiconductor QS6612 is used on the RPX CLLF                  */
+
+/* register definitions */
+
+#define MII_QS6612_MCR		17  /* Mode Control Register      */
+#define MII_QS6612_FTR		27  /* Factory Test Register      */
+#define MII_QS6612_MCO		28  /* Misc. Control Register     */
+#define MII_QS6612_ISR		29  /* Interrupt Source Register  */
+#define MII_QS6612_IMR		30  /* Interrupt Mask Register    */
+#define MII_QS6612_IMR_INIT	0x003a
+#define MII_QS6612_PCR		31  /* 100BaseTx PHY Control Reg. */
+
+#define QS6612_PCR_AN_COMPLETE	0x1000
+#define QS6612_PCR_RLBEN	0x0200
+#define QS6612_PCR_DCREN	0x0100
+#define QS6612_PCR_4B5BEN	0x0040
+#define QS6612_PCR_TX_ISOLATE	0x0020
+#define QS6612_PCR_MLT3_DIS	0x0002
+#define QS6612_PCR_SCRM_DESCRM	0x0001
+
+MODULE_DESCRIPTION("Quality Semiconductor PHY driver");
+MODULE_AUTHOR("Andy Fleming");
+MODULE_LICENSE("GPL");
+
+/* Returns 0, unless there's a write error */
+static int qs6612_config_init(struct phy_device *phydev)
+{
+	/* The PHY powers up isolated on the RPX,
+	 * so send a command to allow operation.
+	 * XXX - My docs indicate this should be 0x0940
+	 * ...or something.  The current value sets three
+	 * reserved bits, bit 11, which specifies it should be
+	 * set to one, bit 10, which specifies it should be set
+	 * to 0, and bit 7, which doesn't specify.  However, my
+	 * docs are preliminary, and I will leave it like this
+	 * until someone more knowledgable corrects me or it.
+	 * -- Andy Fleming
+	 */
+	return phy_write(phydev, MII_QS6612_PCR, 0x0dc0);
+}
+
+static int qs6612_ack_interrupt(struct phy_device *phydev)
+{
+	int err;
+
+	/* The Interrupt Source register is not self-clearing, bits 4 and 5 are
+	 * cleared when MII_BMSR is read and bits 1 and 3 are cleared when
+	 * MII_EXPANSION is read
+	 */
+	err = phy_read(phydev, MII_QS6612_ISR);
+
+	if (err < 0)
+		return err;
+
+	err = phy_read(phydev, MII_BMSR);
+
+	if (err < 0)
+		return err;
+
+	err = phy_read(phydev, MII_EXPANSION);
+
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int qs6612_config_intr(struct phy_device *phydev)
+{
+	int err;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		/* clear any interrupts before enabling them */
+		err = qs6612_ack_interrupt(phydev);
+		if (err)
+			return err;
+
+		err = phy_write(phydev, MII_QS6612_IMR,
+				MII_QS6612_IMR_INIT);
+	} else {
+		err = phy_write(phydev, MII_QS6612_IMR, 0);
+		if (err)
+			return err;
+
+		/* clear any leftover interrupts */
+		err = qs6612_ack_interrupt(phydev);
+	}
+
+	return err;
+
+}
+
+static irqreturn_t qs6612_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	irq_status = phy_read(phydev, MII_QS6612_ISR);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (!(irq_status & MII_QS6612_IMR_INIT))
+		return IRQ_NONE;
+
+	/* the interrupt source register is not self-clearing */
+	qs6612_ack_interrupt(phydev);
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
+static struct phy_driver qs6612_driver[] = { {
+	.phy_id		= 0x00181440,
+	.name		= "QS6612",
+	.phy_id_mask	= 0xfffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_init	= qs6612_config_init,
+	.config_intr	= qs6612_config_intr,
+	.handle_interrupt = qs6612_handle_interrupt,
+} };
+
+module_phy_driver(qs6612_driver);
+
+static const struct mdio_device_id __maybe_unused qs6612_tbl[] = {
+	{ 0x00181440, 0xfffffff0 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, qs6612_tbl);