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, 40 insertions, 0 deletions

diff --git a/net/dsa/dsa.h b/net/dsa/dsa.h
new file mode 100644
index 000000000..3cc7823e9
--- /dev/null
+++ b/net/dsa/dsa.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __DSA_H
+#define __DSA_H
+
+#include <linux/list.h>
+#include <linux/types.h>
+
+struct dsa_db;
+struct dsa_device_ops;
+struct dsa_lag;
+struct dsa_switch_tree;
+struct net_device;
+struct work_struct;
+
+extern struct list_head dsa_tree_list;
+
+bool dsa_db_equal(const struct dsa_db *a, const struct dsa_db *b);
+bool dsa_schedule_work(struct work_struct *work);
+void dsa_lag_map(struct dsa_switch_tree *dst, struct dsa_lag *lag);
+void dsa_lag_unmap(struct dsa_switch_tree *dst, struct dsa_lag *lag);
+struct dsa_lag *dsa_tree_lag_find(struct dsa_switch_tree *dst,
+				  const struct net_device *lag_dev);
+struct net_device *dsa_tree_find_first_conduit(struct dsa_switch_tree *dst);
+int dsa_tree_change_tag_proto(struct dsa_switch_tree *dst,
+			      const struct dsa_device_ops *tag_ops,
+			      const struct dsa_device_ops *old_tag_ops);
+void dsa_tree_conduit_admin_state_change(struct dsa_switch_tree *dst,
+					 struct net_device *conduit,
+					 bool up);
+void dsa_tree_conduit_oper_state_change(struct dsa_switch_tree *dst,
+					struct net_device *conduit,
+					bool up);
+unsigned int dsa_bridge_num_get(const struct net_device *bridge_dev, int max);
+void dsa_bridge_num_put(const struct net_device *bridge_dev,
+			unsigned int bridge_num);
+struct dsa_bridge *dsa_tree_bridge_find(struct dsa_switch_tree *dst,
+					const struct net_device *br);
+
+#endif