mirror of
https://github.com/torvalds/linux.git
synced 2024-11-27 06:31:52 +00:00
b90feaff2a
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
77 lines
1.6 KiB
C
77 lines
1.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* net/sched/em_nbyte.c N-Byte ematch
|
|
*
|
|
* Authors: Thomas Graf <tgraf@suug.ch>
|
|
*/
|
|
|
|
#include <linux/gfp.h>
|
|
#include <linux/module.h>
|
|
#include <linux/types.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/string.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/tc_ematch/tc_em_nbyte.h>
|
|
#include <net/pkt_cls.h>
|
|
|
|
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 -ENOBUFS;
|
|
|
|
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);
|
|
|
|
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_LICENSE("GPL");
|
|
|
|
module_init(init_em_nbyte);
|
|
module_exit(exit_em_nbyte);
|
|
|
|
MODULE_ALIAS_TCF_EMATCH(TCF_EM_NBYTE);
|