From 6daf14140129d30207ed6a0a69851fa6a3636bda Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Thu, 20 Feb 2020 07:59:14 -0600 Subject: netfilter: Replace zero-length array with flexible-array member 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 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva Signed-off-by: Pablo Neira Ayuso --- net/bridge/netfilter/ebtables.c | 2 +- net/ipv4/netfilter/arp_tables.c | 4 ++-- net/ipv4/netfilter/ip_tables.c | 4 ++-- net/ipv6/netfilter/ip6_tables.c | 4 ++-- net/netfilter/ipset/ip_set_bitmap_ip.c | 2 +- net/netfilter/ipset/ip_set_bitmap_ipmac.c | 2 +- net/netfilter/ipset/ip_set_bitmap_port.c | 2 +- net/netfilter/ipset/ip_set_hash_gen.h | 4 ++-- net/netfilter/nfnetlink_acct.c | 2 +- net/netfilter/nft_set_pipapo.c | 2 +- net/netfilter/xt_hashlimit.c | 2 +- net/netfilter/xt_recent.c | 4 ++-- 12 files changed, 17 insertions(+), 17 deletions(-) (limited to 'net') diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c index e1256e03a9a8..78db58c7aec2 100644 --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -1561,7 +1561,7 @@ struct compat_ebt_entry_mwt { 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 */ diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index f1f78a742b36..b167f4a5b684 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -1057,7 +1057,7 @@ struct compat_arpt_replace { 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) @@ -1383,7 +1383,7 @@ static int compat_copy_entries_to_user(unsigned int total_size, 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, diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 10b91ebdf213..c2670eaa74e6 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -1211,7 +1211,7 @@ struct compat_ipt_replace { 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 @@ -1562,7 +1562,7 @@ compat_do_ipt_set_ctl(struct sock *sk, int cmd, void __user *user, 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 diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index c973ace208c5..e27393498ecb 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -1227,7 +1227,7 @@ struct compat_ip6t_replace { 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 @@ -1571,7 +1571,7 @@ compat_do_ip6t_set_ctl(struct sock *sk, int cmd, void __user *user, 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 diff --git a/net/netfilter/ipset/ip_set_bitmap_ip.c b/net/netfilter/ipset/ip_set_bitmap_ip.c index 0a2196f59106..486959f70cf3 100644 --- a/net/netfilter/ipset/ip_set_bitmap_ip.c +++ b/net/netfilter/ipset/ip_set_bitmap_ip.c @@ -46,7 +46,7 @@ struct bitmap_ip { 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)); }; diff --git a/net/netfilter/ipset/ip_set_bitmap_ipmac.c b/net/netfilter/ipset/ip_set_bitmap_ipmac.c index 739e343efaf6..2310a316e0af 100644 --- a/net/netfilter/ipset/ip_set_bitmap_ipmac.c +++ b/net/netfilter/ipset/ip_set_bitmap_ipmac.c @@ -49,7 +49,7 @@ struct bitmap_ipmac { 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)); }; diff --git a/net/netfilter/ipset/ip_set_bitmap_port.c b/net/netfilter/ipset/ip_set_bitmap_port.c index b49978dd810d..e56ced66f202 100644 --- a/net/netfilter/ipset/ip_set_bitmap_port.c +++ b/net/netfilter/ipset/ip_set_bitmap_port.c @@ -37,7 +37,7 @@ struct bitmap_port { 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)); }; diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h index e52d7b7597a0..1ee43752d6d3 100644 --- a/net/netfilter/ipset/ip_set_hash_gen.h +++ b/net/netfilter/ipset/ip_set_hash_gen.h @@ -76,7 +76,7 @@ struct hbucket { 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)); }; @@ -109,7 +109,7 @@ struct htable { 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]) diff --git a/net/netfilter/nfnetlink_acct.c b/net/netfilter/nfnetlink_acct.c index 2481470dec36..5827117f2635 100644 --- a/net/netfilter/nfnetlink_acct.c +++ b/net/netfilter/nfnetlink_acct.c @@ -33,7 +33,7 @@ struct nf_acct { refcount_t refcnt; char name[NFACCT_NAME_MAX]; struct rcu_head rcu_head; - char data[0]; + char data[]; }; struct nfacct_filter { diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c index d752a39b97d6..26395c8188b1 100644 --- a/net/netfilter/nft_set_pipapo.c +++ b/net/netfilter/nft_set_pipapo.c @@ -433,7 +433,7 @@ struct nft_pipapo_match { 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 */ diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c index 8c835ad63729..9c5cfd74a0ee 100644 --- a/net/netfilter/xt_hashlimit.c +++ b/net/netfilter/xt_hashlimit.c @@ -132,7 +132,7 @@ struct xt_hashlimit_htable { const char *name; struct net *net; - struct hlist_head hash[0]; /* hashtable itself */ + struct hlist_head hash[]; /* hashtable itself */ }; static int diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c index 225a7ab6d79a..19bef176145e 100644 --- a/net/netfilter/xt_recent.c +++ b/net/netfilter/xt_recent.c @@ -71,7 +71,7 @@ struct recent_entry { u_int8_t ttl; u_int8_t index; u_int16_t nstamps; - unsigned long stamps[0]; + unsigned long stamps[]; }; struct recent_table { @@ -82,7 +82,7 @@ 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 { -- cgit v1.2.3