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, 86 insertions, 0 deletions

diff --git a/drivers/clk/sprd/composite.h b/drivers/clk/sprd/composite.h
new file mode 100644
index 000000000..15cec97d2
--- /dev/null
+++ b/drivers/clk/sprd/composite.h
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+//
+// Spreadtrum composite clock driver
+//
+// Copyright (C) 2017 Spreadtrum, Inc.
+// Author: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
+
+#ifndef _SPRD_COMPOSITE_H_
+#define _SPRD_COMPOSITE_H_
+
+#include "common.h"
+#include "mux.h"
+#include "div.h"
+
+struct sprd_comp {
+	struct sprd_mux_ssel	mux;
+	struct sprd_div_internal	div;
+	struct sprd_clk_common	common;
+};
+
+#define SPRD_COMP_CLK_HW_INIT_FN(_struct, _name, _parent, _reg, _table,	\
+				 _mshift, _mwidth, _doffset, _dshift,	\
+				 _dwidth, _flags, _fn)			\
+	struct sprd_comp _struct = {					\
+		.mux	= _SPRD_MUX_CLK(_mshift, _mwidth, _table),	\
+		.div	= _SPRD_DIV_CLK(_doffset, _dshift, _dwidth),	\
+		.common = {						\
+			.regmap		= NULL,				\
+			.reg		= _reg,				\
+			.hw.init = _fn(_name, _parent,			\
+				       &sprd_comp_ops, _flags),		\
+		}							\
+	}
+
+#define SPRD_COMP_CLK_TABLE(_struct, _name, _parent, _reg, _table,	\
+			    _mshift, _mwidth, _dshift, _dwidth, _flags)	\
+	SPRD_COMP_CLK_HW_INIT_FN(_struct, _name, _parent, _reg, _table,	\
+				 _mshift, _mwidth, 0x0, _dshift,	\
+				 _dwidth, _flags, CLK_HW_INIT_PARENTS)
+
+#define SPRD_COMP_CLK(_struct, _name, _parent, _reg, _mshift,		\
+		      _mwidth, _dshift, _dwidth, _flags)		\
+	SPRD_COMP_CLK_TABLE(_struct, _name, _parent, _reg, NULL,	\
+			    _mshift, _mwidth, _dshift, _dwidth, _flags)
+
+#define SPRD_COMP_CLK_DATA_TABLE(_struct, _name, _parent, _reg, _table,	\
+				 _mshift, _mwidth, _dshift,		\
+				 _dwidth, _flags)			\
+	SPRD_COMP_CLK_HW_INIT_FN(_struct, _name, _parent, _reg, _table,	\
+				 _mshift, _mwidth, 0x0, _dshift,	\
+				 _dwidth, _flags,			\
+				 CLK_HW_INIT_PARENTS_DATA)
+
+#define SPRD_COMP_CLK_DATA(_struct, _name, _parent, _reg, _mshift,	\
+			   _mwidth, _dshift, _dwidth, _flags)		\
+	SPRD_COMP_CLK_DATA_TABLE(_struct, _name, _parent, _reg, NULL,	\
+				 _mshift, _mwidth, _dshift, _dwidth,	\
+				 _flags)
+
+#define SPRD_COMP_CLK_DATA_TABLE_OFFSET(_struct, _name, _parent, _reg,	\
+					_table, _mshift, _mwidth,	\
+					_doffset, _dshift, _dwidth,	\
+					_flags)				\
+	SPRD_COMP_CLK_HW_INIT_FN(_struct, _name, _parent, _reg, _table,	\
+				 _mshift, _mwidth, _doffset, _dshift,	\
+				 _dwidth, _flags,			\
+				 CLK_HW_INIT_PARENTS_DATA)
+
+#define SPRD_COMP_CLK_DATA_OFFSET(_struct, _name, _parent, _reg,	\
+				  _mshift, _mwidth, _doffset, _dshift,	\
+				  _dwidth, _flags)			\
+	SPRD_COMP_CLK_DATA_TABLE_OFFSET(_struct, _name, _parent, _reg,	\
+					NULL, _mshift, _mwidth,		\
+					_doffset, _dshift, _dwidth,	\
+					_flags)
+
+static inline struct sprd_comp *hw_to_sprd_comp(const struct clk_hw *hw)
+{
+	struct sprd_clk_common *common = hw_to_sprd_clk_common(hw);
+
+	return container_of(common, struct sprd_comp, common);
+}
+
+extern const struct clk_ops sprd_comp_ops;
+
+#endif /* _SPRD_COMPOSITE_H_ */