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, 66 insertions, 0 deletions

diff --git a/drivers/hid/hid-sunplus.c b/drivers/hid/hid-sunplus.c
new file mode 100644
index 000000000..64e4cff8c
--- /dev/null
+++ b/drivers/hid/hid-sunplus.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for some sunplus "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/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+static const __u8 *sp_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	if (*rsize >= 112 && rdesc[104] == 0x26 && rdesc[105] == 0x80 &&
+			rdesc[106] == 0x03) {
+		hid_info(hdev, "fixing up Sunplus Wireless Desktop report descriptor\n");
+		rdesc[105] = rdesc[110] = 0x03;
+		rdesc[106] = rdesc[111] = 0x21;
+	}
+	return rdesc;
+}
+
+#define sp_map_key_clear(c)	hid_map_usage_clear(hi, usage, bit, max, \
+		EV_KEY, (c))
+static int sp_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 0x2003: sp_map_key_clear(KEY_ZOOMIN);		break;
+	case 0x2103: sp_map_key_clear(KEY_ZOOMOUT);	break;
+	default:
+		return 0;
+	}
+	return 1;
+}
+
+static const struct hid_device_id sp_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SUNPLUS, USB_DEVICE_ID_SUNPLUS_WDESKTOP) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, sp_devices);
+
+static struct hid_driver sp_driver = {
+	.name = "sunplus",
+	.id_table = sp_devices,
+	.report_fixup = sp_report_fixup,
+	.input_mapping = sp_input_mapping,
+};
+module_hid_driver(sp_driver);
+
+MODULE_DESCRIPTION("HID driver for some sunplus \"special\" devices");
+MODULE_LICENSE("GPL");