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, 88 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/fuse/nvidia,tegra20-fuse.yaml b/Documentation/devicetree/bindings/fuse/nvidia,tegra20-fuse.yaml
new file mode 100644
index 000000000..02f0b0462
--- /dev/null
+++ b/Documentation/devicetree/bindings/fuse/nvidia,tegra20-fuse.yaml
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/fuse/nvidia,tegra20-fuse.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NVIDIA Tegra FUSE block
+
+maintainers:
+  - Thierry Reding <thierry.reding@gmail.com>
+  - Jon Hunter <jonathanh@nvidia.com>
+
+properties:
+  compatible:
+    oneOf:
+      - enum:
+          - nvidia,tegra20-efuse
+          - nvidia,tegra30-efuse
+          - nvidia,tegra114-efuse
+          - nvidia,tegra124-efuse
+          - nvidia,tegra210-efuse
+          - nvidia,tegra186-efuse
+          - nvidia,tegra194-efuse
+          - nvidia,tegra234-efuse
+
+      - items:
+          - const: nvidia,tegra132-efuse
+          - const: nvidia,tegra124-efuse
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: fuse
+
+  resets:
+    maxItems: 1
+
+  reset-names:
+    items:
+      - const: fuse
+
+  operating-points-v2: true
+
+  power-domains:
+    items:
+      - description: phandle to the core power domain
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+
+if:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - nvidia,tegra20-efuse
+          - nvidia,tegra30-efuse
+          - nvidia,tegra114-efuse
+          - nvidia,tegra124-efuse
+          - nvidia,tegra132-efuse
+          - nvidia,tegra210-efuse
+then:
+  required:
+    - resets
+    - reset-names
+
+examples:
+  - |
+    #include <dt-bindings/clock/tegra20-car.h>
+
+    fuse@7000f800 {
+        compatible = "nvidia,tegra20-efuse";
+        reg = <0x7000f800 0x400>;
+        clocks = <&tegra_car TEGRA20_CLK_FUSE>;
+        clock-names = "fuse";
+        resets = <&tegra_car 39>;
+        reset-names = "fuse";
+    };