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ipv4/inet_sock.h: Avoid thousands of -Wflex-array-member-not-at-end warnings

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Use DEFINE_RAW_FLEX() to avoid thousands of -Wflex-array-member-not-at-end
warnings.

Remove struct ip_options_data, and adjust the rest of the code so that
flexible-array member struct ip_options_rcu::opt.__data[] ends last
in struct icmp_bxm.

Compensate for this by using the DEFINE_RAW_FLEX() helper to define each
on-stack struct instance that contained struct ip_options_data as a member,
and to define struct ip_options_rcu with a fixed on-stack size for its
nested flexible-array member opt.__data[].

Also, add a couple of code comments to prevent people from adding members
to a struct after another member that contains a flexible array.

With these changes, fix 2600 warnings of the following type:

include/net/inet_sock.h:65:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://patch.msgid.link/aVteBadWA6AbTp7X@kspp
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Gustavo A. R. Silva 2026-01-05 15:45:25 +09:00 • committed by Jakub Kicinski
parent 915a5f60ad
commit c86af46b9c
6 changed files with 79 additions and 68 deletions
Download patch file Download diff file Expand all files Collapse all files

9
include/net/inet_sock.h
View file

@ -26,6 +26,8 @@
#include <net/tcp_states.h>
#include <net/l3mdev.h>
#define IP_OPTIONS_DATA_FIXED_SIZE 40
/** struct ip_options - IP Options
*
* @faddr - Saved first hop address
@ -58,12 +60,9 @@ struct ip_options {
struct ip_options_rcu {
struct rcu_head rcu;
struct ip_options opt;
};
struct ip_options_data {
struct ip_options_rcu opt;
char data[40];
/* Must be last as it ends in a flexible-array member. */
struct ip_options opt;
};
struct inet_request_sock {

104
net/ipv4/icmp.c
View file

@ -112,7 +112,9 @@ struct icmp_bxm {
__be32 times[3];
} data;
int head_len;
struct ip_options_data replyopts;
/* Must be last as it ends in a flexible-array member. */
struct ip_options_rcu replyopts;
};
/* An array of errno for error messages from dest unreach. */
@ -353,9 +355,12 @@ void icmp_out_count(struct net *net, unsigned char type)
static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
struct sk_buff *skb)
{
struct icmp_bxm *icmp_param = from;
DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data,
IP_OPTIONS_DATA_FIXED_SIZE);
__wsum csum;
icmp_param = from;
csum = skb_copy_and_csum_bits(icmp_param->skb,
icmp_param->offset + offset,
to, len);
@ -413,7 +418,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
int type = icmp_param->data.icmph.type;
int code = icmp_param->data.icmph.code;
if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
if (ip_options_echo(net, &icmp_param->replyopts.opt, skb))
return;
/* Needed by both icmpv4_global_allow and icmp_xmit_lock */
@ -435,10 +440,10 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
daddr = ipc.addr = ip_hdr(skb)->saddr;
saddr = fib_compute_spec_dst(skb);
if (icmp_param->replyopts.opt.opt.optlen) {
ipc.opt = &icmp_param->replyopts.opt;
if (icmp_param->replyopts.opt.optlen) {
ipc.opt = &icmp_param->replyopts;
if (ipc.opt->opt.srr)
daddr = icmp_param->replyopts.opt.opt.faddr;
daddr = icmp_param->replyopts.opt.faddr;
}
memset(&fl4, 0, sizeof(fl4));
fl4.daddr = daddr;
@ -491,8 +496,8 @@ static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4,
int err;
memset(fl4, 0, sizeof(*fl4));
fl4->daddr = (param->replyopts.opt.opt.srr ?
param->replyopts.opt.opt.faddr : iph->saddr);
fl4->daddr = (param->replyopts.opt.srr ?
param->replyopts.opt.faddr : iph->saddr);
fl4->saddr = saddr;
fl4->flowi4_mark = mark;
fl4->flowi4_uid = sock_net_uid(net, NULL);
@ -775,9 +780,10 @@ free_skb:
void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
const struct inet_skb_parm *parm)
{
DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data,
IP_OPTIONS_DATA_FIXED_SIZE);
struct iphdr *iph;
int room;
struct icmp_bxm icmp_param;
struct rtable *rt = skb_rtable(skb_in);
bool apply_ratelimit = false;
struct sk_buff *ext_skb;
@ -906,7 +912,7 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
iph->tos;
mark = IP4_REPLY_MARK(net, skb_in->mark);
if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in,
if (__ip_options_echo(net, &icmp_param->replyopts.opt, skb_in,
&parm->opt))
goto out_unlock;
@ -915,21 +921,21 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
* Prepare data for ICMP header.
*/
icmp_param.data.icmph.type = type;
icmp_param.data.icmph.code = code;
icmp_param.data.icmph.un.gateway = info;
icmp_param.data.icmph.checksum = 0;
icmp_param.skb = skb_in;
icmp_param.offset = skb_network_offset(skb_in);
icmp_param->data.icmph.type = type;
icmp_param->data.icmph.code = code;
icmp_param->data.icmph.un.gateway = info;
icmp_param->data.icmph.checksum = 0;
icmp_param->skb = skb_in;
icmp_param->offset = skb_network_offset(skb_in);
ipcm_init(&ipc);
ipc.tos = tos;
ipc.addr = iph->saddr;
ipc.opt = &icmp_param.replyopts.opt;
ipc.opt = &icmp_param->replyopts;
ipc.sockc.mark = mark;
rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr,
inet_dsfield_to_dscp(tos), mark, type, code,
&icmp_param);
icmp_param);
if (IS_ERR(rt))
goto out_unlock;
@ -942,7 +948,7 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
room = dst_mtu(&rt->dst);
if (room > 576)
room = 576;
room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.optlen;
room -= sizeof(struct icmphdr);
/* Guard against tiny mtu. We need to include at least one
* IP network header for this message to make any sense.
@ -950,15 +956,15 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
if (room <= (int)sizeof(struct iphdr))
goto ende;
ext_skb = icmp_ext_append(net, skb_in, &icmp_param.data.icmph, room,
ext_skb = icmp_ext_append(net, skb_in, &icmp_param->data.icmph, room,
parm->iif);
if (ext_skb)
icmp_param.skb = ext_skb;
icmp_param->skb = ext_skb;
icmp_param.data_len = icmp_param.skb->len - icmp_param.offset;
if (icmp_param.data_len > room)
icmp_param.data_len = room;
icmp_param.head_len = sizeof(struct icmphdr);
icmp_param->data_len = icmp_param->skb->len - icmp_param->offset;
if (icmp_param->data_len > room)
icmp_param->data_len = room;
icmp_param->head_len = sizeof(struct icmphdr);
/* if we don't have a source address at this point, fall back to the
* dummy address instead of sending out a packet with a source address
@ -969,7 +975,7 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
trace_icmp_send(skb_in, type, code);
icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt);
if (ext_skb)
consume_skb(ext_skb);
@ -1206,7 +1212,8 @@ static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
{
struct icmp_bxm icmp_param;
DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data,
IP_OPTIONS_DATA_FIXED_SIZE);
struct net *net;
net = skb_dst_dev_net_rcu(skb);
@ -1214,18 +1221,18 @@ static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
return SKB_NOT_DROPPED_YET;
icmp_param.data.icmph = *icmp_hdr(skb);
icmp_param.skb = skb;
icmp_param.offset = 0;
icmp_param.data_len = skb->len;
icmp_param.head_len = sizeof(struct icmphdr);
icmp_param->data.icmph = *icmp_hdr(skb);
icmp_param->skb = skb;
icmp_param->offset = 0;
icmp_param->data_len = skb->len;
icmp_param->head_len = sizeof(struct icmphdr);
if (icmp_param.data.icmph.type == ICMP_ECHO)
icmp_param.data.icmph.type = ICMP_ECHOREPLY;
else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
if (icmp_param->data.icmph.type == ICMP_ECHO)
icmp_param->data.icmph.type = ICMP_ECHOREPLY;
else if (!icmp_build_probe(skb, &icmp_param->data.icmph))
return SKB_NOT_DROPPED_YET;
icmp_reply(&icmp_param, skb);
icmp_reply(icmp_param, skb);
return SKB_NOT_DROPPED_YET;
}
@ -1353,7 +1360,8 @@ EXPORT_SYMBOL_GPL(icmp_build_probe);
*/
static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
{
struct icmp_bxm icmp_param;
DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data,
IP_OPTIONS_DATA_FIXED_SIZE);
/*
* Too short.
*/
@ -1363,19 +1371,19 @@ static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
/*
* Fill in the current time as ms since midnight UT:
*/
icmp_param.data.times[1] = inet_current_timestamp();
icmp_param.data.times[2] = icmp_param.data.times[1];
icmp_param->data.times[1] = inet_current_timestamp();
icmp_param->data.times[2] = icmp_param->data.times[1];
BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
BUG_ON(skb_copy_bits(skb, 0, &icmp_param->data.times[0], 4));
icmp_param.data.icmph = *icmp_hdr(skb);
icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
icmp_param.data.icmph.code = 0;
icmp_param.skb = skb;
icmp_param.offset = 0;
icmp_param.data_len = 0;
icmp_param.head_len = sizeof(struct icmphdr) + 12;
icmp_reply(&icmp_param, skb);
icmp_param->data.icmph = *icmp_hdr(skb);
icmp_param->data.icmph.type = ICMP_TIMESTAMPREPLY;
icmp_param->data.icmph.code = 0;
icmp_param->skb = skb;
icmp_param->offset = 0;
icmp_param->data_len = 0;
icmp_param->head_len = sizeof(struct icmphdr) + 12;
icmp_reply(icmp_param, skb);
return SKB_NOT_DROPPED_YET;
out_err:

13
net/ipv4/ip_output.c
View file

@ -1606,7 +1606,8 @@ void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk,
const struct ip_reply_arg *arg,
unsigned int len, u64 transmit_time, u32 txhash)
{
struct ip_options_data replyopts;
DEFINE_RAW_FLEX(struct ip_options_rcu, replyopts, opt.__data,
IP_OPTIONS_DATA_FIXED_SIZE);
struct ipcm_cookie ipc;
struct flowi4 fl4;
struct rtable *rt = skb_rtable(skb);
@ -1615,18 +1616,18 @@ void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk,
int err;
int oif;
if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
if (__ip_options_echo(net, &replyopts->opt, skb, sopt))
return;
ipcm_init(&ipc);
ipc.addr = daddr;
ipc.sockc.transmit_time = transmit_time;
if (replyopts.opt.opt.optlen) {
ipc.opt = &replyopts.opt;
if (replyopts->opt.optlen) {
ipc.opt = replyopts;
if (replyopts.opt.opt.srr)
daddr = replyopts.opt.opt.faddr;
if (replyopts->opt.srr)
daddr = replyopts->opt.faddr;
}
oif = arg->bound_dev_if;

7
net/ipv4/ping.c
View file

@ -690,6 +690,8 @@ EXPORT_IPV6_MOD_GPL(ping_common_sendmsg);
static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
DEFINE_RAW_FLEX(struct ip_options_rcu, opt_copy, opt.__data,
IP_OPTIONS_DATA_FIXED_SIZE);
struct net *net = sock_net(sk);
struct flowi4 fl4;
struct inet_sock *inet = inet_sk(sk);
@ -697,7 +699,6 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
struct icmphdr user_icmph;
struct pingfakehdr pfh;
struct rtable *rt = NULL;
struct ip_options_data opt_copy;
int free = 0;
__be32 saddr, daddr, faddr;
u8 scope;
@ -746,9 +747,9 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
rcu_read_lock();
inet_opt = rcu_dereference(inet->inet_opt);
if (inet_opt) {
memcpy(&opt_copy, inet_opt,
memcpy(opt_copy, inet_opt,
sizeof(*inet_opt) + inet_opt->opt.optlen);
ipc.opt = &opt_copy.opt;
ipc.opt = opt_copy;
}
rcu_read_unlock();
}

7
net/ipv4/raw.c
View file

@ -481,6 +481,8 @@ static int raw_getfrag(void *from, char *to, int offset, int len, int odd,
static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
DEFINE_RAW_FLEX(struct ip_options_rcu, opt_copy, opt.__data,
IP_OPTIONS_DATA_FIXED_SIZE);
struct inet_sock *inet = inet_sk(sk);
struct net *net = sock_net(sk);
struct ipcm_cookie ipc;
@ -491,7 +493,6 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
__be32 daddr;
__be32 saddr;
int uc_index, err;
struct ip_options_data opt_copy;
struct raw_frag_vec rfv;
int hdrincl;
@ -561,9 +562,9 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
rcu_read_lock();
inet_opt = rcu_dereference(inet->inet_opt);
if (inet_opt) {
memcpy(&opt_copy, inet_opt,
memcpy(opt_copy, inet_opt,
sizeof(*inet_opt) + inet_opt->opt.optlen);
ipc.opt = &opt_copy.opt;
ipc.opt = opt_copy;
}
rcu_read_unlock();
}

7
net/ipv4/udp.c
View file

@ -1269,6 +1269,8 @@ EXPORT_IPV6_MOD_GPL(udp_cmsg_send);
int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
DEFINE_RAW_FLEX(struct ip_options_rcu, opt_copy, opt.__data,
IP_OPTIONS_DATA_FIXED_SIZE);
struct inet_sock *inet = inet_sk(sk);
struct udp_sock *up = udp_sk(sk);
DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
@ -1286,7 +1288,6 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
int corkreq = udp_test_bit(CORK, sk) || msg->msg_flags & MSG_MORE;
int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
struct sk_buff *skb;
struct ip_options_data opt_copy;
int uc_index;
if (len > 0xFFFF)
@ -1368,9 +1369,9 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
rcu_read_lock();
inet_opt = rcu_dereference(inet->inet_opt);
if (inet_opt) {
memcpy(&opt_copy, inet_opt,
memcpy(opt_copy, inet_opt,
sizeof(*inet_opt) + inet_opt->opt.optlen);
ipc.opt = &opt_copy.opt;
ipc.opt = opt_copy;
}
rcu_read_unlock();
}