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, 28 insertions, 0 deletions

diff --git a/io_uring/Makefile b/io_uring/Makefile
new file mode 100644
index 000000000..c54e328d1
--- /dev/null
+++ b/io_uring/Makefile
@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for io_uring
+
+ifdef CONFIG_GCOV_PROFILE_URING
+GCOV_PROFILE := y
+endif
+
+obj-$(CONFIG_IO_URING)		+= io_uring.o opdef.o kbuf.o rsrc.o notif.o \
+					tctx.o filetable.o rw.o poll.o \
+					tw.o wait.o eventfd.o uring_cmd.o \
+					openclose.o sqpoll.o xattr.o nop.o \
+					fs.o splice.o sync.o msg_ring.o \
+					advise.o openclose.o statx.o timeout.o \
+					cancel.o waitid.o register.o \
+					truncate.o memmap.o alloc_cache.o \
+					query.o loop.o
+
+obj-$(CONFIG_IO_URING_ZCRX)	+= zcrx.o
+obj-$(CONFIG_IO_WQ)		+= io-wq.o
+obj-$(CONFIG_FUTEX)		+= futex.o
+obj-$(CONFIG_EPOLL)		+= epoll.o
+obj-$(CONFIG_NET_RX_BUSY_POLL)	+= napi.o
+obj-$(CONFIG_NET) += net.o cmd_net.o
+obj-$(CONFIG_PROC_FS) += fdinfo.o
+obj-$(CONFIG_IO_URING_MOCK_FILE) += mock_file.o
+obj-$(CONFIG_IO_URING_BPF) += bpf_filter.o
+obj-$(CONFIG_IO_URING_BPF_OPS) += bpf-ops.o