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 --- fs/netfs/fscache_proc.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 fs/netfs/fscache_proc.c (limited to 'fs/netfs/fscache_proc.c') diff --git a/fs/netfs/fscache_proc.c b/fs/netfs/fscache_proc.c new file mode 100644 index 000000000..874d951bc --- /dev/null +++ b/fs/netfs/fscache_proc.c @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* FS-Cache statistics viewing interface + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#define FSCACHE_DEBUG_LEVEL CACHE +#include +#include +#include +#include "internal.h" + +/* + * Add files to /proc/fs/netfs/. + */ +int __init fscache_proc_init(void) +{ + if (!proc_symlink("fs/fscache", NULL, "netfs")) + goto error_sym; + + if (!proc_create_seq("fs/netfs/caches", S_IFREG | 0444, NULL, + &fscache_caches_seq_ops)) + goto error; + + if (!proc_create_seq("fs/netfs/volumes", S_IFREG | 0444, NULL, + &fscache_volumes_seq_ops)) + goto error; + + if (!proc_create_seq("fs/netfs/cookies", S_IFREG | 0444, NULL, + &fscache_cookies_seq_ops)) + goto error; + return 0; + +error: + remove_proc_entry("fs/fscache", NULL); +error_sym: + return -ENOMEM; +} + +/* + * Clean up the /proc/fs/fscache symlink. + */ +void fscache_proc_cleanup(void) +{ + remove_proc_subtree("fs/fscache", NULL); +} -- cgit v1.3.1