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, 95 insertions, 0 deletions

diff --git a/include/media/dvb_net.h b/include/media/dvb_net.h
new file mode 100644
index 000000000..4a921ea96
--- /dev/null
+++ b/include/media/dvb_net.h
@@ -0,0 +1,95 @@
+/*
+ * dvb_net.h
+ *
+ * Copyright (C) 2001 Ralph Metzler for convergence integrated media GmbH
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _DVB_NET_H_
+#define _DVB_NET_H_
+
+#include <linux/module.h>
+
+#include <media/dvbdev.h>
+
+struct net_device;
+
+#define DVB_NET_DEVICES_MAX 10
+
+#ifdef CONFIG_DVB_NET
+
+/**
+ * struct dvb_net - describes a DVB network interface
+ *
+ * @dvbdev:		pointer to &struct dvb_device.
+ * @device:		array of pointers to &struct net_device.
+ * @state:		array of integers to each net device. A value
+ *			different than zero means that the interface is
+ *			in usage.
+ * @exit:		flag to indicate when the device is being removed.
+ * @demux:		pointer to &struct dmx_demux.
+ * @ioctl_mutex:	protect access to this struct.
+ * @remove_mutex:	mutex that avoids a race condition between a callback
+ *			called when the hardware is disconnected and the
+ *			file_operations of dvb_net.
+ *
+ * Currently, the core supports up to %DVB_NET_DEVICES_MAX (10) network
+ * devices.
+ */
+
+struct dvb_net {
+	struct dvb_device *dvbdev;
+	struct net_device *device[DVB_NET_DEVICES_MAX];
+	int state[DVB_NET_DEVICES_MAX];
+	unsigned int exit:1;
+	struct dmx_demux *demux;
+	struct mutex ioctl_mutex;
+	struct mutex remove_mutex;
+};
+
+/**
+ * dvb_net_init - nitializes a digital TV network device and registers it.
+ *
+ * @adap:	pointer to &struct dvb_adapter.
+ * @dvbnet:	pointer to &struct dvb_net.
+ * @dmxdemux:	pointer to &struct dmx_demux.
+ */
+int dvb_net_init(struct dvb_adapter *adap, struct dvb_net *dvbnet,
+		  struct dmx_demux *dmxdemux);
+
+/**
+ * dvb_net_release - releases a digital TV network device and unregisters it.
+ *
+ * @dvbnet:	pointer to &struct dvb_net.
+ */
+void dvb_net_release(struct dvb_net *dvbnet);
+
+#else
+
+struct dvb_net {
+	struct dvb_device *dvbdev;
+};
+
+static inline void dvb_net_release(struct dvb_net *dvbnet)
+{
+}
+
+static inline int dvb_net_init(struct dvb_adapter *adap,
+			       struct dvb_net *dvbnet, struct dmx_demux *dmx)
+{
+	return 0;
+}
+
+#endif /* ifdef CONFIG_DVB_NET */
+
+#endif