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, 30 insertions, 0 deletions

diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
new file mode 100644
index 000000000..b2a6660bb
--- /dev/null
+++ b/tools/testing/radix-tree/Makefile
@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: GPL-2.0
+
+.PHONY: clean
+
+TARGETS = main idr-test multiorder xarray maple
+CORE_OFILES = $(SHARED_OFILES) xarray.o maple.o test.o
+OFILES = main.o $(CORE_OFILES) regression1.o regression2.o \
+	 regression3.o regression4.o tag_check.o multiorder.o idr-test.o \
+	iteration_check.o iteration_check_2.o benchmark.o
+
+targets: generated/map-shift.h generated/bit-length.h $(TARGETS)
+
+include ../shared/shared.mk
+
+main:	$(OFILES)
+
+xarray.o: ../../../lib/test_xarray.c
+idr-test.o: ../../../lib/test_ida.c
+idr-test: idr-test.o $(CORE_OFILES)
+
+xarray: $(CORE_OFILES) xarray.o
+
+maple: $(CORE_OFILES) maple.o
+
+multiorder: multiorder.o $(CORE_OFILES)
+
+clean:
+	$(RM) $(TARGETS) *.o radix-tree.c idr.c generated/*
+
+$(OFILES): $(SHARED_DEPS) *.h