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, 30 insertions, 0 deletions

diff --git a/drivers/input/misc/adxl34x.h b/drivers/input/misc/adxl34x.h
new file mode 100644
index 000000000..718e90c20
--- /dev/null
+++ b/drivers/input/misc/adxl34x.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * ADXL345/346 Three-Axis Digital Accelerometers (I2C/SPI Interface)
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Copyright (C) 2009 Michael Hennerich, Analog Devices Inc.
+ */
+
+#ifndef _ADXL34X_H_
+#define _ADXL34X_H_
+
+struct device;
+struct adxl34x;
+
+struct adxl34x_bus_ops {
+	u16 bustype;
+	int (*read)(struct device *, unsigned char);
+	int (*read_block)(struct device *, unsigned char, int, void *);
+	int (*write)(struct device *, unsigned char, unsigned char);
+};
+
+struct adxl34x *adxl34x_probe(struct device *dev, int irq,
+			      bool fifo_delay_default,
+			      const struct adxl34x_bus_ops *bops);
+
+extern const struct dev_pm_ops adxl34x_pm;
+extern const struct attribute_group *adxl34x_groups[];
+
+#endif