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-ezkey.c b/drivers/hid/hid-ezkey.c
new file mode 100644
index 000000000..0e28bc0b8
--- /dev/null
+++ b/drivers/hid/hid-ezkey.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for some ezkey "special" devices
+ *
+ *  Copyright (c) 1999 Andreas Gal
+ *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
+ *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
+ *  Copyright (c) 2006-2007 Jiri Kosina
+ *  Copyright (c) 2008 Jiri Slaby
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+#define ez_map_rel(c)	hid_map_usage(hi, usage, bit, max, EV_REL, (c))
+#define ez_map_key(c)	hid_map_usage(hi, usage, bit, max, EV_KEY, (c))
+
+static int ez_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	if ((usage->hid & HID_USAGE_PAGE) != HID_UP_CONSUMER)
+		return 0;
+
+	switch (usage->hid & HID_USAGE) {
+	case 0x230: ez_map_key(BTN_MOUSE);	break;
+	case 0x231: ez_map_rel(REL_WHEEL);	break;
+	/*
+	 * this keyboard has a scrollwheel implemented in
+	 * totally broken way. We map this usage temporarily
+	 * to HWHEEL and handle it in the event quirk handler
+	 */
+	case 0x232: ez_map_rel(REL_HWHEEL);	break;
+	default:
+		return 0;
+	}
+	return 1;
+}
+
+static int ez_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	if (!(hdev->claimed & HID_CLAIMED_INPUT) || !field->hidinput ||
+			!usage->type)
+		return 0;
+
+	/* handle the temporary quirky mapping to HWHEEL */
+	if (usage->type == EV_REL && usage->code == REL_HWHEEL) {
+		struct input_dev *input = field->hidinput->input;
+		input_event(input, usage->type, REL_WHEEL, -value);
+		return 1;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id ez_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_EZKEY, USB_DEVICE_ID_BTC_8193) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, ez_devices);
+
+static struct hid_driver ez_driver = {
+	.name = "ezkey",
+	.id_table = ez_devices,
+	.input_mapping = ez_input_mapping,
+	.event = ez_event,
+};
+module_hid_driver(ez_driver);
+
+MODULE_DESCRIPTION("HID driver for some ezkey \"special\" devices");
+MODULE_LICENSE("GPL");