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]
Lastly, fix checkpatch.pl warning
WARNING: __aligned(size) is preferred over __attribute__((aligned(size)))
in net/bridge/netfilter/ebtables.c
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
80c49dd975f4 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
struct ip_set_comment_rcu {
struct rcu_head rcu;
- char str[0];
+ char str[];
};
struct ip_set_comment {
unsigned int stacksize;
void ***jumpstack;
- unsigned char entries[0] __aligned(8);
+ unsigned char entries[] __aligned(8);
};
int xt_register_target(struct xt_target *target);
} kernel;
u_int16_t match_size;
} u;
- unsigned char data[0];
+ unsigned char data[];
};
struct compat_xt_entry_target {
} kernel;
u_int16_t target_size;
} u;
- unsigned char data[0];
+ unsigned char data[];
};
/* FIXME: this works only on 32 bit tasks
struct compat_xt_counters_info {
char name[XT_TABLE_MAXNAMELEN];
compat_uint_t num_counters;
- struct compat_xt_counters counters[0];
+ struct compat_xt_counters counters[];
};
struct _compat_xt_align {
__u16 next_offset;
compat_uint_t comefrom;
struct compat_xt_counters counters;
- unsigned char elems[0];
+ unsigned char elems[];
};
static inline struct xt_entry_target *
/* room to maintain the stack used for jumping from and into udc */
struct ebt_chainstack **chainstack;
char *entries;
- struct ebt_counter counters[0] ____cacheline_aligned;
+ struct ebt_counter counters[] ____cacheline_aligned;
};
struct ebt_table {
__u16 next_offset;
compat_uint_t comefrom;
struct compat_xt_counters counters;
- unsigned char elems[0];
+ unsigned char elems[];
};
/* Helper functions */
__u16 next_offset;
compat_uint_t comefrom;
struct compat_xt_counters counters;
- unsigned char elems[0];
+ unsigned char elems[];
};
static inline struct xt_entry_target *
struct nf_ct_ext {
u8 offset[NF_CT_EXT_NUM];
u8 len;
- char data[0];
+ char data[];
};
static inline bool __nf_ct_ext_exist(const struct nf_ct_ext *ext, u8 id)
struct nf_ct_timeout {
__u16 l3num;
const struct nf_conntrack_l4proto *l4proto;
- char data[0];
+ char data[];
};
struct ctnl_timeout {
*/
struct nft_userdata {
u8 len;
- unsigned char data[0];
+ unsigned char data[];
};
/**
struct nft_set_ext {
u8 genmask;
u8 offset[NFT_SET_EXT_NUM];
- char data[0];
+ char data[];
};
static inline void nft_set_ext_prepare(struct nft_set_ext_tmpl *tmpl)
int msg_type;
bool put_net;
struct nft_ctx ctx;
- char data[0];
+ char data[];
};
struct nft_trans_rule {
struct ebt_mac_wormhash {
int table[257];
int poolsize;
- struct ebt_mac_wormhash_tuple pool[0];
+ struct ebt_mac_wormhash_tuple pool[];
};
#define ebt_mac_wormhash_size(x) ((x) ? sizeof(struct ebt_mac_wormhash) \
compat_uptr_t ptr;
} u;
compat_uint_t match_size;
- compat_uint_t data[0] __attribute__ ((aligned (__alignof__(struct compat_ebt_replace))));
+ compat_uint_t data[] __aligned(__alignof__(struct compat_ebt_replace));
};
/* account for possible padding between match_size and ->data */
u32 underflow[NF_ARP_NUMHOOKS];
u32 num_counters;
compat_uptr_t counters;
- struct compat_arpt_entry entries[0];
+ struct compat_arpt_entry entries[];
};
static inline void compat_release_entry(struct compat_arpt_entry *e)
struct compat_arpt_get_entries {
char name[XT_TABLE_MAXNAMELEN];
compat_uint_t size;
- struct compat_arpt_entry entrytable[0];
+ struct compat_arpt_entry entrytable[];
};
static int compat_get_entries(struct net *net,
u32 underflow[NF_INET_NUMHOOKS];
u32 num_counters;
compat_uptr_t counters; /* struct xt_counters * */
- struct compat_ipt_entry entries[0];
+ struct compat_ipt_entry entries[];
};
static int
struct compat_ipt_get_entries {
char name[XT_TABLE_MAXNAMELEN];
compat_uint_t size;
- struct compat_ipt_entry entrytable[0];
+ struct compat_ipt_entry entrytable[];
};
static int
u32 underflow[NF_INET_NUMHOOKS];
u32 num_counters;
compat_uptr_t counters; /* struct xt_counters * */
- struct compat_ip6t_entry entries[0];
+ struct compat_ip6t_entry entries[];
};
static int
struct compat_ip6t_get_entries {
char name[XT_TABLE_MAXNAMELEN];
compat_uint_t size;
- struct compat_ip6t_entry entrytable[0];
+ struct compat_ip6t_entry entrytable[];
};
static int
u8 netmask; /* subnet netmask */
struct timer_list gc; /* garbage collection */
struct ip_set *set; /* attached to this ip_set */
- unsigned char extensions[0] /* data extensions */
+ unsigned char extensions[] /* data extensions */
__aligned(__alignof__(u64));
};
size_t memsize; /* members size */
struct timer_list gc; /* garbage collector */
struct ip_set *set; /* attached to this ip_set */
- unsigned char extensions[0] /* MAC + data extensions */
+ unsigned char extensions[] /* MAC + data extensions */
__aligned(__alignof__(u64));
};
size_t memsize; /* members size */
struct timer_list gc; /* garbage collection */
struct ip_set *set; /* attached to this ip_set */
- unsigned char extensions[0] /* data extensions */
+ unsigned char extensions[] /* data extensions */
__aligned(__alignof__(u64));
};
DECLARE_BITMAP(used, AHASH_MAX_TUNED);
u8 size; /* size of the array */
u8 pos; /* position of the first free entry */
- unsigned char value[0] /* the array of the values */
+ unsigned char value[] /* the array of the values */
__aligned(__alignof__(u64));
};
u8 htable_bits; /* size of hash table == 2^htable_bits */
u32 maxelem; /* Maxelem per region */
struct ip_set_region *hregion; /* Region locks and ext sizes */
- struct hbucket __rcu *bucket[0]; /* hashtable buckets */
+ struct hbucket __rcu *bucket[]; /* hashtable buckets */
};
#define hbucket(h, i) ((h)->bucket[i])
refcount_t refcnt;
char name[NFACCT_NAME_MAX];
struct rcu_head rcu_head;
- char data[0];
+ char data[];
};
struct nfacct_filter {
unsigned long * __percpu *scratch;
size_t bsize_max;
struct rcu_head rcu;
- struct nft_pipapo_field f[0];
+ struct nft_pipapo_field f[];
};
/* Current working bitmap index, toggled between field matches */
const char *name;
struct net *net;
- struct hlist_head hash[0]; /* hashtable itself */
+ struct hlist_head hash[]; /* hashtable itself */
};
static int
u_int8_t ttl;
u_int8_t index;
u_int16_t nstamps;
- unsigned long stamps[0];
+ unsigned long stamps[];
};
struct recent_table {
unsigned int entries;
u8 nstamps_max_mask;
struct list_head lru_list;
- struct list_head iphash[0];
+ struct list_head iphash[];
};
struct recent_net {
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