diff options
| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-17 14:01:11 -0600 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-02-17 19:05:05 -0800 |
| commit | 45a4296b6e55ef2fbbe5946582822daf8f0f2e71 (patch) | |
| tree | dc7844286facbf4b8eb78270c8afe7140fb782af /net | |
| parent | 9814428a44d63bf77831afdbb37b5f0aab7394c9 (diff) | |
bpf, sockmap: 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]
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: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/sock_map.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 085cef5857bb..3a7a96ab088a 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -518,7 +518,7 @@ struct bpf_htab_elem { u32 hash; struct sock *sk; struct hlist_node node; - u8 key[0]; + u8 key[]; }; struct bpf_htab_bucket { |