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, 79 insertions, 0 deletions

diff --git a/drivers/hid/hid-speedlink.c b/drivers/hid/hid-speedlink.c
new file mode 100644
index 000000000..22ee078c4
--- /dev/null
+++ b/drivers/hid/hid-speedlink.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for Speedlink Vicious and Divine Cezanne (USB mouse).
+ *  Fixes "jumpy" cursor and removes nonexistent keyboard LEDS from
+ *  the HID descriptor.
+ *
+ *  Copyright (c) 2011, 2013 Stefan Kriwanek <dev@stefankriwanek.de>
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+static const struct hid_device_id speedlink_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_X_TENSIONS, USB_DEVICE_ID_SPEEDLINK_VAD_CEZANNE)},
+	{ }
+};
+
+static int speedlink_input_mapping(struct hid_device *hdev,
+		struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	/*
+	 * The Cezanne mouse has a second "keyboard" USB endpoint for it is
+	 * able to map keyboard events to the button presses.
+	 * It sends a standard keyboard report descriptor, though, whose
+	 * LEDs we ignore.
+	 */
+	switch (usage->hid & HID_USAGE_PAGE) {
+	case HID_UP_LED:
+		return -1;
+	}
+	return 0;
+}
+
+static int speedlink_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	/* No other conditions due to usage_table. */
+
+	/* This fixes the "jumpy" cursor occuring due to invalid events sent
+	 * by the device. Some devices only send them with value==+256, others
+	 * don't. However, catching abs(value)>=256 is restrictive enough not
+	 * to interfere with devices that were bug-free (has been tested).
+	 */
+	if (abs(value) >= 256)
+		return 1;
+	/* Drop useless distance 0 events (on button clicks etc.) as well */
+	if (value == 0)
+		return 1;
+
+	return 0;
+}
+
+MODULE_DEVICE_TABLE(hid, speedlink_devices);
+
+static const struct hid_usage_id speedlink_grabbed_usages[] = {
+	{ HID_GD_X, EV_REL, 0 },
+	{ HID_GD_Y, EV_REL, 1 },
+	{ HID_ANY_ID - 1, HID_ANY_ID - 1, HID_ANY_ID - 1}
+};
+
+static struct hid_driver speedlink_driver = {
+	.name = "speedlink",
+	.id_table = speedlink_devices,
+	.usage_table = speedlink_grabbed_usages,
+	.input_mapping = speedlink_input_mapping,
+	.event = speedlink_event,
+};
+module_hid_driver(speedlink_driver);
+
+MODULE_DESCRIPTION("HID driver for Speedlink Vicious and Divine Cezanne (USB mouse)");
+MODULE_LICENSE("GPL");