From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall 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 Signed-off-by: Stafford Horne --- samples/kdb/Makefile | 2 ++ samples/kdb/kdb_hello.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 60 insertions(+) create mode 100644 samples/kdb/Makefile create mode 100644 samples/kdb/kdb_hello.c (limited to 'samples/kdb') diff --git a/samples/kdb/Makefile b/samples/kdb/Makefile new file mode 100644 index 000000000..947cb8522 --- /dev/null +++ b/samples/kdb/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_SAMPLE_KDB) += kdb_hello.o diff --git a/samples/kdb/kdb_hello.c b/samples/kdb/kdb_hello.c new file mode 100644 index 000000000..82736e5a5 --- /dev/null +++ b/samples/kdb/kdb_hello.c @@ -0,0 +1,58 @@ +/* + * Created by: Jason Wessel + * + * Copyright (c) 2010 Wind River Systems, Inc. All Rights Reserved. + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#include +#include + +/* + * All kdb shell command call backs receive argc and argv, where + * argv[0] is the command the end user typed + */ +static int kdb_hello_cmd(int argc, const char **argv) +{ + if (argc > 1) + return KDB_ARGCOUNT; + + if (argc) + kdb_printf("Hello %s.\n", argv[1]); + else + kdb_printf("Hello world!\n"); + + return 0; +} + +static kdbtab_t hello_cmd = { + .name = "hello", + .func = kdb_hello_cmd, + .usage = "[string]", + .help = "Say Hello World or Hello [string]", +}; + +static int __init kdb_hello_cmd_init(void) +{ + /* + * Registration of a dynamically added kdb command is done with + * kdb_register(). + */ + kdb_register(&hello_cmd); + return 0; +} + +static void __exit kdb_hello_cmd_exit(void) +{ + kdb_unregister(&hello_cmd); +} + +module_init(kdb_hello_cmd_init); +module_exit(kdb_hello_cmd_exit); + +MODULE_AUTHOR("WindRiver"); +MODULE_DESCRIPTION("KDB example to add a hello command"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1