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>

2 files changed, 111 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/csky/cpus.txt b/Documentation/devicetree/bindings/csky/cpus.txt
new file mode 100644
index 000000000..ae79412f2
--- /dev/null
+++ b/Documentation/devicetree/bindings/csky/cpus.txt
@@ -0,0 +1,73 @@
+==================
+C-SKY CPU Bindings
+==================
+
+The device tree allows to describe the layout of CPUs in a system through
+the "cpus" node, which in turn contains a number of subnodes (ie "cpu")
+defining properties for every cpu.
+
+Only SMP system need to care about the cpus node and single processor
+needn't define cpus node at all.
+
+=====================================
+cpus and cpu node bindings definition
+=====================================
+
+- cpus node
+
+	Description: Container of cpu nodes
+
+	The node name must be "cpus".
+
+	A cpus node must define the following properties:
+
+	- #address-cells
+		Usage: required
+		Value type: <u32>
+		Definition: must be set to 1
+	- #size-cells
+		Usage: required
+		Value type: <u32>
+		Definition: must be set to 0
+
+- cpu node
+
+	Description: Describes one of SMP cores
+
+	PROPERTIES
+
+	- device_type
+		Usage: required
+		Value type: <string>
+		Definition: must be "cpu"
+	- reg
+		Usage: required
+		Value type: <u32>
+		Definition: CPU index
+	- compatible:
+		Usage: required
+		Value type: <string>
+		Definition: must contain "csky", eg:
+			"csky,610"
+			"csky,807"
+			"csky,810"
+			"csky,860"
+
+Example:
+--------
+
+	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		cpu@0 {
+			device_type = "cpu";
+			reg = <0>;
+			status = "ok";
+		};
+
+		cpu@1 {
+			device_type = "cpu";
+			reg = <1>;
+			status = "ok";
+		};
+	};
diff --git a/Documentation/devicetree/bindings/csky/pmu.txt b/Documentation/devicetree/bindings/csky/pmu.txt
new file mode 100644
index 000000000..728d05ca6
--- /dev/null
+++ b/Documentation/devicetree/bindings/csky/pmu.txt
@@ -0,0 +1,38 @@
+===============================
+C-SKY Performance Monitor Units
+===============================
+
+C-SKY Performance Monitor is designed for ck807/ck810/ck860 SMP soc and
+it could count cpu's events for helping analysis performance issues.
+
+============================
+PMU node bindings definition
+============================
+
+	Description: Describes PMU
+
+	PROPERTIES
+
+	- compatible
+		Usage: required
+		Value type: <string>
+		Definition: must be "csky,csky-pmu"
+	- interrupts
+		Usage: required
+		Value type: <u32 IRQ_TYPE_XXX>
+		Definition: must be pmu irq num defined by soc
+	- count-width
+		Usage: optional
+		Value type: <u32>
+		Definition: the width of pmu counter
+
+Examples:
+---------
+#include <dt-bindings/interrupt-controller/irq.h>
+
+	pmu: performace-monitor {
+		compatible = "csky,csky-pmu";
+		interrupts = <23 IRQ_TYPE_EDGE_RISING>;
+		interrupt-parent = <&intc>;
+		count-width = <48>;
+        };