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, 98 insertions, 0 deletions

diff --git a/drivers/hid/hid-retrode.c b/drivers/hid/hid-retrode.c
new file mode 100644
index 000000000..7997627fd
--- /dev/null
+++ b/drivers/hid/hid-retrode.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for Retrode 2 controller adapter and plug-in extensions
+ *
+ *  Copyright (c) 2017 Bastien Nocera <hadess@hadess.net>
+ */
+
+/*
+ */
+
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include "hid-ids.h"
+
+#define CONTROLLER_NAME_BASE "Retrode"
+
+static int retrode_input_configured(struct hid_device *hdev,
+					struct hid_input *hi)
+{
+	struct hid_field *field = hi->report->field[0];
+	const char *suffix;
+	int number = 0;
+	char *name;
+
+	switch (field->report->id) {
+	case 0:
+		suffix = "SNES Mouse";
+		break;
+	case 1:
+	case 2:
+		suffix = "SNES / N64";
+		number = field->report->id;
+		break;
+	case 3:
+	case 4:
+		suffix = "Mega Drive";
+		number = field->report->id - 2;
+		break;
+	default:
+		hid_err(hdev, "Got unhandled report id %d\n", field->report->id);
+		suffix = "Unknown";
+	}
+
+	if (number)
+		name = devm_kasprintf(&hdev->dev, GFP_KERNEL,
+				"%s %s #%d", CONTROLLER_NAME_BASE,
+				suffix, number);
+	else
+		name = devm_kasprintf(&hdev->dev, GFP_KERNEL,
+				"%s %s", CONTROLLER_NAME_BASE, suffix);
+
+	if (!name)
+		return -ENOMEM;
+
+	hi->input->name = name;
+
+	return 0;
+}
+
+static int retrode_probe(struct hid_device *hdev,
+			const struct hid_device_id *id)
+{
+
+	int ret;
+
+	/* Has no effect on the mouse device */
+	hdev->quirks |= HID_QUIRK_MULTI_INPUT;
+
+	ret = hid_parse(hdev);
+	if (ret)
+		return ret;
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static const struct hid_device_id retrode_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_FUTURE_TECHNOLOGY, USB_DEVICE_ID_RETRODE2) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, retrode_devices);
+
+static struct hid_driver retrode_driver = {
+	.name             = "hid-retrode",
+	.id_table         = retrode_devices,
+	.input_configured = retrode_input_configured,
+	.probe            = retrode_probe,
+};
+
+module_hid_driver(retrode_driver);
+
+MODULE_DESCRIPTION("HID driver for Retrode 2 controller adapter and plug-in extensions");
+MODULE_LICENSE("GPL");