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, 38 insertions, 0 deletions

diff --git a/drivers/clk/sprd/common.h b/drivers/clk/sprd/common.h
new file mode 100644
index 000000000..1d077b39c
--- /dev/null
+++ b/drivers/clk/sprd/common.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+//
+// Spreadtrum clock infrastructure
+//
+// Copyright (C) 2017 Spreadtrum, Inc.
+// Author: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
+
+#ifndef _SPRD_CLK_COMMON_H_
+#define _SPRD_CLK_COMMON_H_
+
+#include <linux/clk-provider.h>
+#include <linux/of_platform.h>
+#include <linux/regmap.h>
+
+struct device_node;
+
+struct sprd_clk_common {
+	struct regmap	*regmap;
+	u32		reg;
+	struct clk_hw	hw;
+};
+
+struct sprd_clk_desc {
+	struct sprd_clk_common		**clk_clks;
+	unsigned long			num_clk_clks;
+	struct clk_hw_onecell_data      *hw_clks;
+};
+
+static inline struct sprd_clk_common *
+	hw_to_sprd_clk_common(const struct clk_hw *hw)
+{
+	return container_of(hw, struct sprd_clk_common, hw);
+}
+int sprd_clk_regmap_init(struct platform_device *pdev,
+			 const struct sprd_clk_desc *desc);
+int sprd_clk_probe(struct device *dev, struct clk_hw_onecell_data *clkhw);
+
+#endif /* _SPRD_CLK_COMMON_H_ */