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, 57 insertions, 0 deletions

diff --git a/drivers/hid/hid-vivaldi.c b/drivers/hid/hid-vivaldi.c
new file mode 100644
index 000000000..cda5938fb
--- /dev/null
+++ b/drivers/hid/hid-vivaldi.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HID support for Vivaldi Keyboard
+ *
+ * Copyright 2020 Google LLC.
+ * Author: Sean O'Brien <seobrien@chromium.org>
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/input/vivaldi-fmap.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include "hid-vivaldi-common.h"
+
+static int vivaldi_probe(struct hid_device *hdev,
+			 const struct hid_device_id *id)
+{
+	struct vivaldi_data *drvdata;
+	int ret;
+
+	drvdata = devm_kzalloc(&hdev->dev, sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	hid_set_drvdata(hdev, drvdata);
+
+	ret = hid_parse(hdev);
+	if (ret)
+		return ret;
+
+	return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+}
+
+static const struct hid_device_id vivaldi_table[] = {
+	{ HID_DEVICE(HID_BUS_ANY, HID_GROUP_VIVALDI, HID_ANY_ID, HID_ANY_ID) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(hid, vivaldi_table);
+
+static struct hid_driver hid_vivaldi = {
+	.name = "hid-vivaldi",
+	.id_table = vivaldi_table,
+	.probe = vivaldi_probe,
+	.feature_mapping = vivaldi_feature_mapping,
+	.driver = {
+		.dev_groups = vivaldi_attribute_groups,
+	},
+};
+
+module_hid_driver(hid_vivaldi);
+
+MODULE_AUTHOR("Sean O'Brien");
+MODULE_DESCRIPTION("HID vivaldi driver");
+MODULE_LICENSE("GPL");