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, 50 insertions, 0 deletions

diff --git a/drivers/hid/hid-penmount.c b/drivers/hid/hid-penmount.c
new file mode 100644
index 000000000..b9edc8e75
--- /dev/null
+++ b/drivers/hid/hid-penmount.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for PenMount touchscreens
+ *
+ *  Copyright (c) 2014 Christian Gmeiner <christian.gmeiner <at> gmail.com>
+ *
+ *  based on hid-penmount copyrighted by
+ *    PenMount Touch Solutions <penmount <at> seed.net.tw>
+ */
+
+/*
+ */
+
+#include <linux/module.h>
+#include <linux/hid.h>
+#include "hid-ids.h"
+
+static int penmount_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_BUTTON) {
+		if (((usage->hid - 1) & HID_USAGE) == 0) {
+			hid_map_usage(hi, usage, bit, max, EV_KEY, BTN_TOUCH);
+			return 1;
+		} else {
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id penmount_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_PENMOUNT, USB_DEVICE_ID_PENMOUNT_6000) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, penmount_devices);
+
+static struct hid_driver penmount_driver = {
+	.name = "hid-penmount",
+	.id_table = penmount_devices,
+	.input_mapping = penmount_input_mapping,
+};
+
+module_hid_driver(penmount_driver);
+
+MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@gmail.com>");
+MODULE_DESCRIPTION("PenMount HID TouchScreen driver");
+MODULE_LICENSE("GPL");