mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-21 16:29:59 +00:00
c61a2a76e5
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>
114 lines
2.8 KiB
C
114 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef LINUX_MLD_H
|
|
#define LINUX_MLD_H
|
|
|
|
#include <linux/in6.h>
|
|
#include <linux/icmpv6.h>
|
|
|
|
/* MLDv1 Query/Report/Done */
|
|
struct mld_msg {
|
|
struct icmp6hdr mld_hdr;
|
|
struct in6_addr mld_mca;
|
|
};
|
|
|
|
#define mld_type mld_hdr.icmp6_type
|
|
#define mld_code mld_hdr.icmp6_code
|
|
#define mld_cksum mld_hdr.icmp6_cksum
|
|
#define mld_maxdelay mld_hdr.icmp6_maxdelay
|
|
#define mld_reserved mld_hdr.icmp6_dataun.un_data16[1]
|
|
|
|
/* Multicast Listener Discovery version 2 headers */
|
|
/* MLDv2 Report */
|
|
struct mld2_grec {
|
|
__u8 grec_type;
|
|
__u8 grec_auxwords;
|
|
__be16 grec_nsrcs;
|
|
struct in6_addr grec_mca;
|
|
struct in6_addr grec_src[];
|
|
};
|
|
|
|
struct mld2_report {
|
|
struct icmp6hdr mld2r_hdr;
|
|
struct mld2_grec mld2r_grec[];
|
|
};
|
|
|
|
#define mld2r_type mld2r_hdr.icmp6_type
|
|
#define mld2r_resv1 mld2r_hdr.icmp6_code
|
|
#define mld2r_cksum mld2r_hdr.icmp6_cksum
|
|
#define mld2r_resv2 mld2r_hdr.icmp6_dataun.un_data16[0]
|
|
#define mld2r_ngrec mld2r_hdr.icmp6_dataun.un_data16[1]
|
|
|
|
/* MLDv2 Query */
|
|
struct mld2_query {
|
|
struct icmp6hdr mld2q_hdr;
|
|
struct in6_addr mld2q_mca;
|
|
#if defined(__LITTLE_ENDIAN_BITFIELD)
|
|
__u8 mld2q_qrv:3,
|
|
mld2q_suppress:1,
|
|
mld2q_resv2:4;
|
|
#elif defined(__BIG_ENDIAN_BITFIELD)
|
|
__u8 mld2q_resv2:4,
|
|
mld2q_suppress:1,
|
|
mld2q_qrv:3;
|
|
#else
|
|
#error "Please fix <asm/byteorder.h>"
|
|
#endif
|
|
__u8 mld2q_qqic;
|
|
__be16 mld2q_nsrcs;
|
|
struct in6_addr mld2q_srcs[];
|
|
};
|
|
|
|
#define mld2q_type mld2q_hdr.icmp6_type
|
|
#define mld2q_code mld2q_hdr.icmp6_code
|
|
#define mld2q_cksum mld2q_hdr.icmp6_cksum
|
|
#define mld2q_mrc mld2q_hdr.icmp6_maxdelay
|
|
#define mld2q_resv1 mld2q_hdr.icmp6_dataun.un_data16[1]
|
|
|
|
/* RFC3810, 5.1.3. Maximum Response Code:
|
|
*
|
|
* If Maximum Response Code >= 32768, Maximum Response Code represents a
|
|
* floating-point value as follows:
|
|
*
|
|
* 0 1 2 3 4 5 6 7 8 9 A B C D E F
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
* |1| exp | mant |
|
|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
*/
|
|
#define MLDV2_MRC_EXP(value) (((value) >> 12) & 0x0007)
|
|
#define MLDV2_MRC_MAN(value) ((value) & 0x0fff)
|
|
|
|
/* RFC3810, 5.1.9. QQIC (Querier's Query Interval Code):
|
|
*
|
|
* If QQIC >= 128, QQIC represents a floating-point value as follows:
|
|
*
|
|
* 0 1 2 3 4 5 6 7
|
|
* +-+-+-+-+-+-+-+-+
|
|
* |1| exp | mant |
|
|
* +-+-+-+-+-+-+-+-+
|
|
*/
|
|
#define MLDV2_QQIC_EXP(value) (((value) >> 4) & 0x07)
|
|
#define MLDV2_QQIC_MAN(value) ((value) & 0x0f)
|
|
|
|
#define MLD_EXP_MIN_LIMIT 32768UL
|
|
#define MLDV1_MRD_MAX_COMPAT (MLD_EXP_MIN_LIMIT - 1)
|
|
|
|
static inline unsigned long mldv2_mrc(const struct mld2_query *mlh2)
|
|
{
|
|
/* RFC3810, 5.1.3. Maximum Response Code */
|
|
unsigned long ret, mc_mrc = ntohs(mlh2->mld2q_mrc);
|
|
|
|
if (mc_mrc < MLD_EXP_MIN_LIMIT) {
|
|
ret = mc_mrc;
|
|
} else {
|
|
unsigned long mc_man, mc_exp;
|
|
|
|
mc_exp = MLDV2_MRC_EXP(mc_mrc);
|
|
mc_man = MLDV2_MRC_MAN(mc_mrc);
|
|
|
|
ret = (mc_man | 0x1000) << (mc_exp + 3);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
#endif
|