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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-02-20 07:59:14 -0600
committerPablo Neira Ayuso <pablo@netfilter.org>2020-03-15 15:20:16 +0100
commit6daf14140129d30207ed6a0a69851fa6a3636bda (patch)
tree43f5f5d662db9cfc241ba1c848f17694b95a16ff /net/ipv6
parenteb9d7af3b7bd6d1b51c6522de53a5bf9c57e81db (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/ipv6')
-rw-r--r--net/ipv6/netfilter/ip6_tables.c4
1 files changed, 2 insertions, 2 deletions
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