diff options
| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-27 03:17:44 +0300 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-02-28 03:21:02 +0300 |
| commit | d7f10df86202273155a9d8f8553bc2ad28e0dd46 (patch) | |
| tree | e253c06e6c409afbff1f057a5376fc77ac1dc01f /include | |
| parent | 4bc988464bb193d67c93ddb2fcd1de127d815b6c (diff) | |
| download | linux-d7f10df86202273155a9d8f8553bc2ad28e0dd46.tar.xz | |
bpf: 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: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200227001744.GA3317@embeddedor
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/bpf-cgroup.h | 2 | ||||
| -rw-r--r-- | include/linux/bpf.h | 2 | ||||
| -rw-r--r-- | include/uapi/linux/bpf.h | 2 |
3 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h index a11d5b7dbbf3..a7cd5c7a2509 100644 --- a/include/linux/bpf-cgroup.h +++ b/include/linux/bpf-cgroup.h @@ -36,7 +36,7 @@ struct bpf_cgroup_storage_map; struct bpf_storage_buffer { struct rcu_head rcu; - char data[0]; + char data[]; }; struct bpf_cgroup_storage { diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 1acd5bf70350..9aa33b8f3d55 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -859,7 +859,7 @@ struct bpf_prog_array_item { struct bpf_prog_array { struct rcu_head rcu; - struct bpf_prog_array_item items[0]; + struct bpf_prog_array_item items[]; }; struct bpf_prog_array *bpf_prog_array_alloc(u32 prog_cnt, gfp_t flags); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 906e9f2752db..8e98ced0963b 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -73,7 +73,7 @@ struct bpf_insn { /* Key of an a BPF_MAP_TYPE_LPM_TRIE entry */ struct bpf_lpm_trie_key { __u32 prefixlen; /* up to 32 for AF_INET, 128 for AF_INET6 */ - __u8 data[0]; /* Arbitrary size */ + __u8 data[]; /* Arbitrary size */ }; struct bpf_cgroup_storage_key { |