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, 53 insertions, 0 deletions

diff --git a/drivers/input/misc/ad714x.h b/drivers/input/misc/ad714x.h
new file mode 100644
index 000000000..dafa12325
--- /dev/null
+++ b/drivers/input/misc/ad714x.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * AD714X CapTouch Programmable Controller driver (bus interfaces)
+ *
+ * Copyright 2009-2011 Analog Devices Inc.
+ */
+
+#ifndef _AD714X_H_
+#define _AD714X_H_
+
+#include <linux/pm.h>
+#include <linux/types.h>
+
+#define STAGE_NUM              12
+
+struct device;
+struct ad714x_platform_data;
+struct ad714x_driver_data;
+struct ad714x_chip;
+
+typedef int (*ad714x_read_t)(struct ad714x_chip *, unsigned short, unsigned short *, size_t);
+typedef int (*ad714x_write_t)(struct ad714x_chip *, unsigned short, unsigned short);
+
+struct ad714x_chip {
+	unsigned short l_state;
+	unsigned short h_state;
+	unsigned short c_state;
+	unsigned short adc_reg[STAGE_NUM];
+	unsigned short amb_reg[STAGE_NUM];
+	unsigned short sensor_val[STAGE_NUM];
+
+	struct ad714x_platform_data *hw;
+	struct ad714x_driver_data *sw;
+
+	int irq;
+	struct device *dev;
+	ad714x_read_t read;
+	ad714x_write_t write;
+
+	struct mutex mutex;
+
+	unsigned product;
+	unsigned version;
+
+	__be16 xfer_buf[16] ____cacheline_aligned;
+
+};
+
+extern const struct dev_pm_ops ad714x_pm;
+struct ad714x_chip *ad714x_probe(struct device *dev, u16 bus_type, int irq,
+				 ad714x_read_t read, ad714x_write_t write);
+
+#endif