diff options
author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-20 16:59:14 +0300 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2020-03-15 17:20:16 +0300 |
commit | 6daf14140129d30207ed6a0a69851fa6a3636bda (patch) | |
tree | 43f5f5d662db9cfc241ba1c848f17694b95a16ff /net/netfilter/ipset/ip_set_hash_gen.h | |
parent | eb9d7af3b7bd6d1b51c6522de53a5bf9c57e81db (diff) | |
download | linux-6daf14140129d30207ed6a0a69851fa6a3636bda.tar.xz |
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/netfilter/ipset/ip_set_hash_gen.h')
-rw-r--r-- | net/netfilter/ipset/ip_set_hash_gen.h | 4 |
1 files changed, 2 insertions, 2 deletions
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]) |