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 --- init/noinitramfs.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 init/noinitramfs.c (limited to 'init/noinitramfs.c') diff --git a/init/noinitramfs.c b/init/noinitramfs.c new file mode 100644 index 000000000..d1d26b93d --- /dev/null +++ b/init/noinitramfs.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * init/noinitramfs.c + * + * Copyright (C) 2006, NXP Semiconductors, All Rights Reserved + * Author: Jean-Paul Saman + */ +#include +#include +#include +#include +#include +#include + +/* + * Create a simple rootfs that is similar to the default initramfs + */ +static int __init default_rootfs(void) +{ + int err; + + usermodehelper_enable(); + err = init_mkdir("/dev", 0755); + if (err < 0) + goto out; + + err = init_mknod("/dev/console", S_IFCHR | S_IRUSR | S_IWUSR, + new_encode_dev(MKDEV(5, 1))); + if (err < 0) + goto out; + + err = init_mkdir("/root", 0700); + if (err < 0) + goto out; + + return 0; + +out: + printk(KERN_WARNING "Failed to create a rootfs\n"); + return err; +} +rootfs_initcall(default_rootfs); -- cgit v1.3.1