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, 33 insertions, 0 deletions

diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile
new file mode 100644
index 000000000..2e8a6b71a
--- /dev/null
+++ b/lib/kunit/Makefile
@@ -0,0 +1,33 @@
+obj-$(CONFIG_KUNIT) +=			kunit.o
+
+kunit-objs +=				test.o \
+					resource.o \
+					user_alloc.o \
+					static_stub.o \
+					string-stream.o \
+					assert.o \
+					try-catch.o \
+					executor.o \
+					attributes.o \
+					device.o \
+					platform.o \
+					bug.o
+
+ifeq ($(CONFIG_KUNIT_DEBUGFS),y)
+kunit-objs +=				debugfs.o
+endif
+
+# KUnit 'hooks' are built-in even when KUnit is built as a module.
+obj-$(if $(CONFIG_KUNIT),y) +=		hooks.o
+
+obj-$(CONFIG_KUNIT_TEST) +=		kunit-test.o
+obj-$(CONFIG_KUNIT_TEST) +=		platform-test.o
+obj-$(CONFIG_KUNIT_TEST) +=		backtrace-suppression-test.o
+
+# string-stream-test compiles built-in only.
+ifeq ($(CONFIG_KUNIT_TEST),y)
+obj-$(CONFIG_KUNIT_TEST) +=		string-stream-test.o
+obj-$(CONFIG_KUNIT_TEST) +=		assert_test.o
+endif
+
+obj-$(CONFIG_KUNIT_EXAMPLE_TEST) +=	kunit-example-test.o