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authorGustavo A. R. Silva2020-02-20 07:59:14 -0600
committerPablo Neira Ayuso2020-03-15 15:20:16 +0100
commit6daf14140129d30207ed6a0a69851fa6a3636bda (patch)
tree43f5f5d662db9cfc241ba1c848f17694b95a16ff /net/bridge
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/bridge')
-rw-r--r--net/bridge/netfilter/ebtables.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index e1256e03a9a8..78db58c7aec2 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -1561,7 +1561,7 @@ struct compat_ebt_entry_mwt {
compat_uptr_t ptr;
} u;
compat_uint_t match_size;
- compat_uint_t data[0] __attribute__ ((aligned (__alignof__(struct compat_ebt_replace))));
+ compat_uint_t data[] __aligned(__alignof__(struct compat_ebt_replace));
};
/* account for possible padding between match_size and ->data */