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, 29 insertions, 0 deletions

diff --git a/tools/testing/vsock/Makefile b/tools/testing/vsock/Makefile
new file mode 100644
index 000000000..88211fd13
--- /dev/null
+++ b/tools/testing/vsock/Makefile
@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-2.0-only
+all: test vsock_perf
+test: vsock_test vsock_diag_test vsock_uring_test
+vsock_test: vsock_test.o vsock_test_zerocopy.o timeout.o control.o util.o msg_zerocopy_common.o
+vsock_diag_test: vsock_diag_test.o timeout.o control.o util.o
+vsock_perf: vsock_perf.o msg_zerocopy_common.o
+
+vsock_test: LDLIBS = -lpthread
+vsock_uring_test: LDLIBS = -luring
+vsock_uring_test: control.o util.o vsock_uring_test.o timeout.o msg_zerocopy_common.o
+
+CFLAGS += -g -O2 -Werror -Wall -I. -I../../include -I../../../usr/include -Wno-pointer-sign -fno-strict-overflow -fno-strict-aliasing -fno-common -MMD -U_FORTIFY_SOURCE -D_GNU_SOURCE
+.PHONY: all test clean
+clean:
+	${RM} *.o *.d vsock_test vsock_diag_test vsock_perf vsock_uring_test
+-include *.d
+
+VSOCK_INSTALL_PATH ?=
+
+install: all
+ifdef VSOCK_INSTALL_PATH
+	mkdir -p $(VSOCK_INSTALL_PATH)
+	install -m 744 vsock_test $(VSOCK_INSTALL_PATH)
+	install -m 744 vsock_perf $(VSOCK_INSTALL_PATH)
+	install -m 744 vsock_diag_test $(VSOCK_INSTALL_PATH)
+	install -m 744 vsock_uring_test $(VSOCK_INSTALL_PATH)
+else
+	$(error Error: set VSOCK_INSTALL_PATH to use install)
+endif