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>

12 files changed, 12 insertions, 0 deletions

diff --git a/scripts/dtc/include-prefixes/arc b/scripts/dtc/include-prefixes/arc
new file mode 120000
index 000000000..5d21b5a69
--- /dev/null
+++ b/scripts/dtc/include-prefixes/arc
@@ -0,0 +1 @@
+../../../arch/arc/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/arm b/scripts/dtc/include-prefixes/arm
new file mode 120000
index 000000000..eb14d4515
--- /dev/null
+++ b/scripts/dtc/include-prefixes/arm
@@ -0,0 +1 @@
+../../../arch/arm/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/arm64 b/scripts/dtc/include-prefixes/arm64
new file mode 120000
index 000000000..275c42c21
--- /dev/null
+++ b/scripts/dtc/include-prefixes/arm64
@@ -0,0 +1 @@
+../../../arch/arm64/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/dt-bindings b/scripts/dtc/include-prefixes/dt-bindings
new file mode 120000
index 000000000..04fdbb3af
--- /dev/null
+++ b/scripts/dtc/include-prefixes/dt-bindings
@@ -0,0 +1 @@
+../../../include/dt-bindings
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/microblaze b/scripts/dtc/include-prefixes/microblaze
new file mode 120000
index 000000000..d9830330a
--- /dev/null
+++ b/scripts/dtc/include-prefixes/microblaze
@@ -0,0 +1 @@
+../../../arch/microblaze/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/mips b/scripts/dtc/include-prefixes/mips
new file mode 120000
index 000000000..ae8d4948d
--- /dev/null
+++ b/scripts/dtc/include-prefixes/mips
@@ -0,0 +1 @@
+../../../arch/mips/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/nios2 b/scripts/dtc/include-prefixes/nios2
new file mode 120000
index 000000000..51772336d
--- /dev/null
+++ b/scripts/dtc/include-prefixes/nios2
@@ -0,0 +1 @@
+../../../arch/nios2/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/openrisc b/scripts/dtc/include-prefixes/openrisc
new file mode 120000
index 000000000..71c3bc75c
--- /dev/null
+++ b/scripts/dtc/include-prefixes/openrisc
@@ -0,0 +1 @@
+../../../arch/openrisc/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/powerpc b/scripts/dtc/include-prefixes/powerpc
new file mode 120000
index 000000000..7cd6ec16e
--- /dev/null
+++ b/scripts/dtc/include-prefixes/powerpc
@@ -0,0 +1 @@
+../../../arch/powerpc/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/riscv b/scripts/dtc/include-prefixes/riscv
new file mode 120000
index 000000000..202509418
--- /dev/null
+++ b/scripts/dtc/include-prefixes/riscv
@@ -0,0 +1 @@
+../../../arch/riscv/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/sh b/scripts/dtc/include-prefixes/sh
new file mode 120000
index 000000000..67d37808c
--- /dev/null
+++ b/scripts/dtc/include-prefixes/sh
@@ -0,0 +1 @@
+../../../arch/sh/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/xtensa b/scripts/dtc/include-prefixes/xtensa
new file mode 120000
index 000000000..d1eaf6ec7
--- /dev/null
+++ b/scripts/dtc/include-prefixes/xtensa
@@ -0,0 +1 @@
+../../../arch/xtensa/boot/dts
\ No newline at end of file