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, 37 insertions, 0 deletions

diff --git a/include/rdma/ib_sysfs.h b/include/rdma/ib_sysfs.h
new file mode 100644
index 000000000..3b77cfd74
--- /dev/null
+++ b/include/rdma/ib_sysfs.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause */
+/*
+ * Copyright (c) 2021 Mellanox Technologies Ltd.  All rights reserved.
+ */
+#ifndef DEF_RDMA_IB_SYSFS_H
+#define DEF_RDMA_IB_SYSFS_H
+
+#include <linux/sysfs.h>
+
+struct ib_device;
+
+struct ib_port_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct ib_device *ibdev, u32 port_num,
+			struct ib_port_attribute *attr, char *buf);
+	ssize_t (*store)(struct ib_device *ibdev, u32 port_num,
+			 struct ib_port_attribute *attr, const char *buf,
+			 size_t count);
+};
+
+#define IB_PORT_ATTR_RW(_name)                                                 \
+	struct ib_port_attribute ib_port_attr_##_name = __ATTR_RW(_name)
+
+#define IB_PORT_ATTR_ADMIN_RW(_name)                                           \
+	struct ib_port_attribute ib_port_attr_##_name =                        \
+		__ATTR_RW_MODE(_name, 0600)
+
+#define IB_PORT_ATTR_RO(_name)                                                 \
+	struct ib_port_attribute ib_port_attr_##_name = __ATTR_RO(_name)
+
+#define IB_PORT_ATTR_WO(_name)                                                 \
+	struct ib_port_attribute ib_port_attr_##_name = __ATTR_WO(_name)
+
+struct ib_device *ib_port_sysfs_get_ibdev_kobj(struct kobject *kobj,
+					       u32 *port_num);
+
+#endif