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 /include/linux/netfilter | |
| 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 'include/linux/netfilter')
| -rw-r--r-- | include/linux/netfilter/ipset/ip_set.h | 2 | ||||
| -rw-r--r-- | include/linux/netfilter/x_tables.h | 8 |
2 files changed, 5 insertions, 5 deletions
diff --git a/include/linux/netfilter/ipset/ip_set.h b/include/linux/netfilter/ipset/ip_set.h index 5448c8b443db..ab192720e2d6 100644 --- a/include/linux/netfilter/ipset/ip_set.h +++ b/include/linux/netfilter/ipset/ip_set.h @@ -98,7 +98,7 @@ struct ip_set_counter { struct ip_set_comment_rcu { struct rcu_head rcu; - char str[0]; + char str[]; }; struct ip_set_comment { diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index 1b261c51b3a3..5da88451853b 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -264,7 +264,7 @@ struct xt_table_info { unsigned int stacksize; void ***jumpstack; - unsigned char entries[0] __aligned(8); + unsigned char entries[] __aligned(8); }; int xt_register_target(struct xt_target *target); @@ -464,7 +464,7 @@ struct compat_xt_entry_match { } kernel; u_int16_t match_size; } u; - unsigned char data[0]; + unsigned char data[]; }; struct compat_xt_entry_target { @@ -480,7 +480,7 @@ 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 @@ -494,7 +494,7 @@ struct compat_xt_counters { 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 { |