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, 54 insertions, 0 deletions

diff --git a/drivers/mfd/madera.h b/drivers/mfd/madera.h
new file mode 100644
index 000000000..900205678
--- /dev/null
+++ b/drivers/mfd/madera.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * MFD internals for Cirrus Logic Madera codecs
+ *
+ * Copyright 2015-2018 Cirrus Logic
+ */
+
+#ifndef MADERA_MFD_H
+#define MADERA_MFD_H
+
+#include <linux/of.h>
+#include <linux/pm.h>
+
+struct madera;
+
+extern const struct dev_pm_ops madera_pm_ops;
+extern const struct of_device_id madera_of_match[];
+
+int madera_dev_init(struct madera *madera);
+int madera_dev_exit(struct madera *madera);
+
+const char *madera_name_from_type(enum madera_type type);
+
+extern const struct regmap_config cs47l15_16bit_spi_regmap;
+extern const struct regmap_config cs47l15_32bit_spi_regmap;
+extern const struct regmap_config cs47l15_16bit_i2c_regmap;
+extern const struct regmap_config cs47l15_32bit_i2c_regmap;
+int cs47l15_patch(struct madera *madera);
+
+extern const struct regmap_config cs47l35_16bit_spi_regmap;
+extern const struct regmap_config cs47l35_32bit_spi_regmap;
+extern const struct regmap_config cs47l35_16bit_i2c_regmap;
+extern const struct regmap_config cs47l35_32bit_i2c_regmap;
+int cs47l35_patch(struct madera *madera);
+
+extern const struct regmap_config cs47l85_16bit_spi_regmap;
+extern const struct regmap_config cs47l85_32bit_spi_regmap;
+extern const struct regmap_config cs47l85_16bit_i2c_regmap;
+extern const struct regmap_config cs47l85_32bit_i2c_regmap;
+int cs47l85_patch(struct madera *madera);
+
+extern const struct regmap_config cs47l90_16bit_spi_regmap;
+extern const struct regmap_config cs47l90_32bit_spi_regmap;
+extern const struct regmap_config cs47l90_16bit_i2c_regmap;
+extern const struct regmap_config cs47l90_32bit_i2c_regmap;
+int cs47l90_patch(struct madera *madera);
+
+extern const struct regmap_config cs47l92_16bit_spi_regmap;
+extern const struct regmap_config cs47l92_32bit_spi_regmap;
+extern const struct regmap_config cs47l92_16bit_i2c_regmap;
+extern const struct regmap_config cs47l92_32bit_i2c_regmap;
+int cs47l92_patch(struct madera *madera);
+
+#endif