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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 /include/linux/netfilter
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 'include/linux/netfilter')
-rw-r--r--include/linux/netfilter/ipset/ip_set.h2
-rw-r--r--include/linux/netfilter/x_tables.h8
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 {