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, 27 insertions, 0 deletions

diff --git a/drivers/input/mouse/focaltech.h b/drivers/input/mouse/focaltech.h
new file mode 100644
index 000000000..0d9023254
--- /dev/null
+++ b/drivers/input/mouse/focaltech.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Focaltech TouchPad PS/2 mouse driver
+ *
+ * Copyright (c) 2014 Red Hat Inc.
+ * Copyright (c) 2014 Mathias Gottschlag <mgottschlag@gmail.com>
+ *
+ * Red Hat authors:
+ *
+ * Hans de Goede <hdegoede@redhat.com>
+ */
+
+#ifndef _FOCALTECH_H
+#define _FOCALTECH_H
+
+int focaltech_detect(struct psmouse *psmouse, bool set_properties);
+
+#ifdef CONFIG_MOUSE_PS2_FOCALTECH
+int focaltech_init(struct psmouse *psmouse);
+#else
+static inline int focaltech_init(struct psmouse *psmouse)
+{
+	return -ENOSYS;
+}
+#endif
+
+#endif