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, 227 insertions, 0 deletions

diff --git a/drivers/net/usb/gl620a.c b/drivers/net/usb/gl620a.c
new file mode 100644
index 000000000..09afd137b
--- /dev/null
+++ b/drivers/net/usb/gl620a.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GeneSys GL620USB-A based links
+ * Copyright (C) 2001 by Jiun-Jie Huang <huangjj@genesyslogic.com.tw>
+ * Copyright (C) 2001 by Stanislav Brabec <utx@penguin.cz>
+ */
+
+// #define	DEBUG			// error path messages, extra info
+// #define	VERBOSE			// more; success messages
+
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/ethtool.h>
+#include <linux/workqueue.h>
+#include <linux/mii.h>
+#include <linux/usb.h>
+#include <linux/usb/usbnet.h>
+#include <linux/gfp.h>
+
+
+/*
+ * GeneSys GL620USB-A (www.genesyslogic.com.tw)
+ *
+ * ... should partially interop with the Win32 driver for this hardware.
+ * The GeneSys docs imply there's some NDIS issue motivating this framing.
+ *
+ * Some info from GeneSys:
+ *  - GL620USB-A is full duplex; GL620USB is only half duplex for bulk.
+ *    (Some cables, like the BAFO-100c, use the half duplex version.)
+ *  - For the full duplex model, the low bit of the version code says
+ *    which side is which ("left/right").
+ *  - For the half duplex type, a control/interrupt handshake settles
+ *    the transfer direction.  (That's disabled here, partially coded.)
+ *    A control URB would block until other side writes an interrupt.
+ *
+ * Original code from Jiun-Jie Huang <huangjj@genesyslogic.com.tw>
+ * and merged into "usbnet" by Stanislav Brabec <utx@penguin.cz>.
+ */
+
+// control msg write command
+#define GENELINK_CONNECT_WRITE			0xF0
+// interrupt pipe index
+#define GENELINK_INTERRUPT_PIPE			0x03
+// interrupt read buffer size
+#define INTERRUPT_BUFSIZE			0x08
+// interrupt pipe interval value
+#define GENELINK_INTERRUPT_INTERVAL		0x10
+// max transmit packet number per transmit
+#define GL_MAX_TRANSMIT_PACKETS			32
+// max packet length
+#define GL_MAX_PACKET_LEN			1514
+// max receive buffer size
+#define GL_RCV_BUF_SIZE		\
+	(((GL_MAX_PACKET_LEN + 4) * GL_MAX_TRANSMIT_PACKETS) + 4)
+
+struct gl_packet {
+	__le32		packet_length;
+	char		packet_data[];
+};
+
+struct gl_header {
+	__le32			packet_count;
+	struct gl_packet	packets;
+};
+
+static int genelink_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+{
+	struct gl_header	*header;
+	struct gl_packet	*packet;
+	struct sk_buff		*gl_skb;
+	u32			size;
+	u32			count;
+
+	/* This check is no longer done by usbnet */
+	if (skb->len < dev->net->hard_header_len)
+		return 0;
+
+	header = (struct gl_header *) skb->data;
+
+	// get the packet count of the received skb
+	count = le32_to_cpu(header->packet_count);
+	if (count > GL_MAX_TRANSMIT_PACKETS) {
+		netdev_dbg(dev->net,
+			   "genelink: invalid received packet count %u\n",
+			   count);
+		return 0;
+	}
+
+	// set the current packet pointer to the first packet
+	packet = &header->packets;
+
+	// decrement the length for the packet count size 4 bytes
+	skb_pull(skb, 4);
+
+	while (count > 1) {
+		// get the packet length
+		size = le32_to_cpu(packet->packet_length);
+
+		// this may be a broken packet
+		if (size > GL_MAX_PACKET_LEN) {
+			netdev_dbg(dev->net, "genelink: invalid rx length %d\n",
+				   size);
+			return 0;
+		}
+
+		if (!skb_pull(skb, size + 4))
+			return 0;
+
+		// allocate the skb for the individual packet
+		gl_skb = alloc_skb(size, GFP_ATOMIC);
+		if (gl_skb) {
+
+			// copy the packet data to the new skb
+			skb_put_data(gl_skb, packet->packet_data, size);
+			usbnet_skb_return(dev, gl_skb);
+		}
+
+		// advance to the next packet
+		packet = (struct gl_packet *)&packet->packet_data[size];
+		count--;
+	}
+
+	// skip the packet length field 4 bytes
+	skb_pull(skb, 4);
+
+	if (skb->len > GL_MAX_PACKET_LEN) {
+		netdev_dbg(dev->net, "genelink: invalid rx length %d\n",
+			   skb->len);
+		return 0;
+	}
+	return 1;
+}
+
+static struct sk_buff *
+genelink_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
+{
+	int 	padlen;
+	int	length = skb->len;
+	int	headroom = skb_headroom(skb);
+	int	tailroom = skb_tailroom(skb);
+	__le32	*packet_count;
+	__le32	*packet_len;
+
+	// FIXME:  magic numbers, bleech
+	padlen = ((skb->len + (4 + 4*1)) % 64) ? 0 : 1;
+
+	if ((!skb_cloned(skb))
+			&& ((headroom + tailroom) >= (padlen + (4 + 4*1)))) {
+		if ((headroom < (4 + 4*1)) || (tailroom < padlen)) {
+			skb->data = memmove(skb->head + (4 + 4*1),
+					     skb->data, skb->len);
+			skb_set_tail_pointer(skb, skb->len);
+		}
+	} else {
+		struct sk_buff	*skb2;
+		skb2 = skb_copy_expand(skb, (4 + 4*1) , padlen, flags);
+		dev_kfree_skb_any(skb);
+		skb = skb2;
+		if (!skb)
+			return NULL;
+	}
+
+	// attach the packet count to the header
+	packet_count = skb_push(skb, (4 + 4 * 1));
+	packet_len = packet_count + 1;
+
+	*packet_count = cpu_to_le32(1);
+	*packet_len = cpu_to_le32(length);
+
+	// add padding byte
+	if ((skb->len % dev->maxpacket) == 0)
+		skb_put(skb, 1);
+
+	return skb;
+}
+
+static int genelink_bind(struct usbnet *dev, struct usb_interface *intf)
+{
+	dev->hard_mtu = GL_RCV_BUF_SIZE;
+	dev->net->hard_header_len += 4;
+	return usbnet_get_endpoints(dev, intf);
+}
+
+static const struct driver_info	genelink_info = {
+	.description =	"Genesys GeneLink",
+	.flags =	FLAG_POINTTOPOINT | FLAG_FRAMING_GL | FLAG_NO_SETINT,
+	.bind =		genelink_bind,
+	.rx_fixup =	genelink_rx_fixup,
+	.tx_fixup =	genelink_tx_fixup,
+
+	.in = 1, .out = 2,
+
+#ifdef	GENELINK_ACK
+	.check_connect =genelink_check_connect,
+#endif
+};
+
+static const struct usb_device_id	products [] = {
+
+{
+	USB_DEVICE(0x05e3, 0x0502),	// GL620USB-A
+	.driver_info =	(unsigned long) &genelink_info,
+},
+	/* NOT: USB_DEVICE(0x05e3, 0x0501),	// GL620USB
+	 * that's half duplex, not currently supported
+	 */
+	{ },		// END
+};
+MODULE_DEVICE_TABLE(usb, products);
+
+static struct usb_driver gl620a_driver = {
+	.name =		"gl620a",
+	.id_table =	products,
+	.probe =	usbnet_probe,
+	.disconnect =	usbnet_disconnect,
+	.suspend =	usbnet_suspend,
+	.resume =	usbnet_resume,
+	.disable_hub_initiated_lpm = 1,
+};
+
+module_usb_driver(gl620a_driver);
+
+MODULE_AUTHOR("Jiun-Jie Huang");
+MODULE_DESCRIPTION("GL620-USB-A Host-to-Host Link cables");
+MODULE_LICENSE("GPL");
+