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, 49 insertions, 0 deletions

diff --git a/net/rxrpc/Makefile b/net/rxrpc/Makefile
new file mode 100644
index 000000000..f994f9f30
--- /dev/null
+++ b/net/rxrpc/Makefile
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for Linux kernel RxRPC
+#
+
+obj-$(CONFIG_AF_RXRPC) += rxrpc.o
+
+rxrpc-y := \
+	af_rxrpc.o \
+	call_accept.o \
+	call_event.o \
+	call_object.o \
+	call_state.o \
+	conn_client.o \
+	conn_event.o \
+	conn_object.o \
+	conn_service.o \
+	input.o \
+	input_rack.o \
+	insecure.o \
+	io_thread.o \
+	key.o \
+	local_event.o \
+	local_object.o \
+	misc.o \
+	net_ns.o \
+	oob.o \
+	output.o \
+	peer_event.o \
+	peer_object.o \
+	recvmsg.o \
+	rtt.o \
+	security.o \
+	sendmsg.o \
+	server_key.o \
+	skbuff.o \
+	txbuf.o \
+	utils.o
+
+rxrpc-$(CONFIG_PROC_FS) += proc.o
+rxrpc-$(CONFIG_RXKAD) += rxkad.o fcrypt.o
+rxrpc-$(CONFIG_SYSCTL) += sysctl.o
+rxrpc-$(CONFIG_RXGK) += \
+	rxgk.o \
+	rxgk_app.o \
+	rxgk_kdf.o
+
+obj-$(CONFIG_RXPERF) += rxperf.o
+obj-$(CONFIG_KUNIT) += tests/