diff options
| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-27 23:58:44 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-03-01 08:27:02 +0300 |
| commit | b90feaff2a2cbf339069adec4bfd6091cfb44b50 (patch) | |
| tree | 93bd8729ec50413d5a530bb7567abf4302de0fbd /net | |
| parent | 9f0ca0c1a50a7de5c71970aa452941199ed210d9 (diff) | |
| download | linux-b90feaff2a2cbf339069adec4bfd6091cfb44b50.tar.xz | |
net: sched: 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/sched/em_ipt.c | 2 | ||||
| -rw-r--r-- | net/sched/em_nbyte.c | 2 | ||||
| -rw-r--r-- | net/sched/sch_atm.c | 2 | ||||
| -rw-r--r-- | net/sched/sch_netem.c | 2 |
4 files changed, 4 insertions, 4 deletions
diff --git a/net/sched/em_ipt.c b/net/sched/em_ipt.c index 9fff6480acc6..eecfe072c508 100644 --- a/net/sched/em_ipt.c +++ b/net/sched/em_ipt.c @@ -22,7 +22,7 @@ struct em_ipt_match { const struct xt_match *match; u32 hook; u8 nfproto; - u8 match_data[0] __aligned(8); + u8 match_data[] __aligned(8); }; struct em_ipt_xt_match { diff --git a/net/sched/em_nbyte.c b/net/sched/em_nbyte.c index 88c7ce42df7e..2c1192a2ee5e 100644 --- a/net/sched/em_nbyte.c +++ b/net/sched/em_nbyte.c @@ -16,7 +16,7 @@ struct nbyte_data { struct tcf_em_nbyte hdr; - char pattern[0]; + char pattern[]; }; static int em_nbyte_change(struct net *net, void *data, int data_len, diff --git a/net/sched/sch_atm.c b/net/sched/sch_atm.c index f4f9b8cdbffb..ee12ca9f55b4 100644 --- a/net/sched/sch_atm.c +++ b/net/sched/sch_atm.c @@ -58,7 +58,7 @@ struct atm_flow_data { struct atm_flow_data *excess; /* flow for excess traffic; NULL to set CLP instead */ int hdr_len; - unsigned char hdr[0]; /* header data; MUST BE LAST */ + unsigned char hdr[]; /* header data; MUST BE LAST */ }; struct atm_qdisc_data { diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c index 42e557d48e4e..84f82771cdf5 100644 --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -66,7 +66,7 @@ struct disttable { u32 size; - s16 table[0]; + s16 table[]; }; struct netem_sched_data { |