diff options
author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-23 17:59:00 -0500 |
---|---|---|
committer | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-04-18 15:44:55 -0500 |
commit | 0ead33642f1df89699f2e4dda8eea59c326b68f6 (patch) | |
tree | bca8a2fdcf0f8d5fd2402c68915316b9bab887d1 | |
parent | 89f60a5d9bf5a6b9b16dfdd56a91c4a2d7b8830d (diff) |
igmp.h: 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>
-rw-r--r-- | include/linux/igmp.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/igmp.h b/include/linux/igmp.h index 463047d0190b..faa6586a5783 100644 --- a/include/linux/igmp.h +++ b/include/linux/igmp.h @@ -38,7 +38,7 @@ struct ip_sf_socklist { unsigned int sl_max; unsigned int sl_count; struct rcu_head rcu; - __be32 sl_addr[0]; + __be32 sl_addr[]; }; #define IP_SFLSIZE(count) (sizeof(struct ip_sf_socklist) + \ |