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, 33 insertions, 0 deletions

diff --git a/include/acpi/acpi.h b/include/acpi/acpi.h
new file mode 100644
index 000000000..07e3d6e21
--- /dev/null
+++ b/include/acpi/acpi.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 */
+/******************************************************************************
+ *
+ * Name: acpi.h - Master public include file used to interface to ACPICA
+ *
+ * Copyright (C) 2000 - 2026, Intel Corp.
+ *
+ *****************************************************************************/
+
+#ifndef __ACPI_H__
+#define __ACPI_H__
+
+/*
+ * Public include files for use by code that will interface to ACPICA.
+ *
+ * Information includes the ACPICA data types, names, exceptions, and
+ * external interface prototypes. Also included are the definitions for
+ * all ACPI tables (FADT, MADT, etc.)
+ *
+ * Note: The order of these include files is important.
+ */
+#include <acpi/platform/acenv.h>	/* Environment-specific items */
+#include <acpi/acnames.h>		/* Common ACPI names and strings */
+#include <acpi/actypes.h>		/* ACPICA data types and structures */
+#include <acpi/acexcep.h>		/* ACPICA exceptions */
+#include <acpi/actbl.h>		/* ACPI table definitions */
+#include <acpi/acrestyp.h>		/* Resource Descriptor structs */
+#include <acpi/platform/acenvex.h>	/* Extra environment-specific items */
+#include <acpi/acoutput.h>		/* Error output and Debug macros */
+#include <acpi/acpiosxf.h>		/* OSL interfaces (ACPICA-to-OS) */
+#include <acpi/acpixf.h>		/* ACPI core subsystem external interfaces */
+
+#endif				/* __ACPI_H__ */