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 --- net/sched/em_nbyte.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 79 insertions(+) create mode 100644 net/sched/em_nbyte.c (limited to 'net/sched/em_nbyte.c') diff --git a/net/sched/em_nbyte.c b/net/sched/em_nbyte.c new file mode 100644 index 000000000..c65ffa5ff --- /dev/null +++ b/net/sched/em_nbyte.c @@ -0,0 +1,79 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * net/sched/em_nbyte.c N-Byte ematch + * + * Authors: Thomas Graf + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +struct nbyte_data { + struct tcf_em_nbyte hdr; + char pattern[]; +}; + +static int em_nbyte_change(struct net *net, void *data, int data_len, + struct tcf_ematch *em) +{ + struct tcf_em_nbyte *nbyte = data; + + if (data_len < sizeof(*nbyte) || + data_len < (sizeof(*nbyte) + nbyte->len)) + return -EINVAL; + + em->datalen = sizeof(*nbyte) + nbyte->len; + em->data = (unsigned long)kmemdup(data, em->datalen, GFP_KERNEL); + if (em->data == 0UL) + return -ENOMEM; + + return 0; +} + +static int em_nbyte_match(struct sk_buff *skb, struct tcf_ematch *em, + struct tcf_pkt_info *info) +{ + struct nbyte_data *nbyte = (struct nbyte_data *) em->data; + unsigned char *ptr = tcf_get_base_ptr(skb, nbyte->hdr.layer); + + if (!ptr) + return 0; + ptr += nbyte->hdr.off; + + if (!tcf_valid_offset(skb, ptr, nbyte->hdr.len)) + return 0; + + return !memcmp(ptr, nbyte->pattern, nbyte->hdr.len); +} + +static struct tcf_ematch_ops em_nbyte_ops = { + .kind = TCF_EM_NBYTE, + .change = em_nbyte_change, + .match = em_nbyte_match, + .owner = THIS_MODULE, + .link = LIST_HEAD_INIT(em_nbyte_ops.link) +}; + +static int __init init_em_nbyte(void) +{ + return tcf_em_register(&em_nbyte_ops); +} + +static void __exit exit_em_nbyte(void) +{ + tcf_em_unregister(&em_nbyte_ops); +} + +MODULE_DESCRIPTION("ematch classifier for arbitrary skb multi-bytes"); +MODULE_LICENSE("GPL"); + +module_init(init_em_nbyte); +module_exit(exit_em_nbyte); + +MODULE_ALIAS_TCF_EMATCH(TCF_EM_NBYTE); -- cgit v1.3.1