diff options
| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-20 07:59:14 -0600 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2020-03-15 15:20:16 +0100 |
| commit | 6daf14140129d30207ed6a0a69851fa6a3636bda (patch) | |
| tree | 43f5f5d662db9cfc241ba1c848f17694b95a16ff /net/ipv4 | |
| parent | eb9d7af3b7bd6d1b51c6522de53a5bf9c57e81db (diff) | |
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 <gustavo@embeddedor.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/netfilter/arp_tables.c | 4 | ||||
| -rw-r--r-- | net/ipv4/netfilter/ip_tables.c | 4 |
2 files changed, 4 insertions, 4 deletions
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 |