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, 43 insertions, 0 deletions

diff --git a/net/batman-adv/mesh-interface.h b/net/batman-adv/mesh-interface.h
new file mode 100644
index 000000000..5e1e83e04
--- /dev/null
+++ b/net/batman-adv/mesh-interface.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) B.A.T.M.A.N. contributors:
+ *
+ * Marek Lindner
+ */
+
+#ifndef _NET_BATMAN_ADV_MESH_INTERFACE_H_
+#define _NET_BATMAN_ADV_MESH_INTERFACE_H_
+
+#include "main.h"
+
+#include <linux/kref.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/types.h>
+
+int batadv_skb_head_push(struct sk_buff *skb, unsigned int len);
+void batadv_interface_rx(struct net_device *mesh_iface,
+			 struct sk_buff *skb, int hdr_size,
+			 struct batadv_orig_node *orig_node);
+bool batadv_meshif_is_valid(const struct net_device *net_dev);
+extern struct rtnl_link_ops batadv_link_ops;
+int batadv_meshif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid);
+void batadv_meshif_destroy_vlan(struct batadv_priv *bat_priv,
+				struct batadv_meshif_vlan *vlan);
+void batadv_meshif_vlan_release(struct kref *ref);
+struct batadv_meshif_vlan *batadv_meshif_vlan_get(struct batadv_priv *bat_priv,
+						  unsigned short vid);
+
+/**
+ * batadv_meshif_vlan_put() - decrease the vlan object refcounter and
+ *  possibly release it
+ * @vlan: the vlan object to release
+ */
+static inline void batadv_meshif_vlan_put(struct batadv_meshif_vlan *vlan)
+{
+	if (!vlan)
+		return;
+
+	kref_put(&vlan->refcount, batadv_meshif_vlan_release);
+}
+
+#endif /* _NET_BATMAN_ADV_MESH_INTERFACE_H_ */