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, 35 insertions, 0 deletions

diff --git a/drivers/pinctrl/pinctrl-utils.h b/drivers/pinctrl/pinctrl-utils.h
new file mode 100644
index 000000000..203fba257
--- /dev/null
+++ b/drivers/pinctrl/pinctrl-utils.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Utils functions to implement the pincontrol driver.
+ *
+ * Copyright (c) 2013, NVIDIA Corporation.
+ *
+ * Author: Laxman Dewangan <ldewangan@nvidia.com>
+ */
+#ifndef __PINCTRL_UTILS_H__
+#define __PINCTRL_UTILS_H__
+
+#include <linux/pinctrl/machine.h>
+
+struct pinctrl_dev;
+struct pinctrl_map;
+
+int pinctrl_utils_reserve_map(struct pinctrl_dev *pctldev,
+		struct pinctrl_map **map, unsigned int *reserved_maps,
+		unsigned int *num_maps, unsigned int reserve);
+int pinctrl_utils_add_map_mux(struct pinctrl_dev *pctldev,
+		struct pinctrl_map **map, unsigned int *reserved_maps,
+		unsigned int *num_maps, const char *group,
+		const char *function);
+int pinctrl_utils_add_map_configs(struct pinctrl_dev *pctldev,
+		struct pinctrl_map **map, unsigned int *reserved_maps,
+		unsigned int *num_maps, const char *group,
+		unsigned long *configs, unsigned int num_configs,
+		enum pinctrl_map_type type);
+int pinctrl_utils_add_config(struct pinctrl_dev *pctldev,
+		unsigned long **configs, unsigned int *num_configs,
+		unsigned long config);
+void pinctrl_utils_free_map(struct pinctrl_dev *pctldev,
+		struct pinctrl_map *map, unsigned int num_maps);
+
+#endif /* __PINCTRL_UTILS_H__ */