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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-02-17 15:43:00 -0600
committerSimon Wunderlich <sw@simonwunderlich.de>2020-02-17 22:43:42 +0100
commit5f27eb055d5c5814785fb9cf0ae4a4c150a8f334 (patch)
tree3a1726556bcc3d7fe7fdae9aa695f75575667e9b /net/batman-adv
parent3b2582c7affde5f30bcc8321385507e66f4299e1 (diff)
batman-adv: 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: Sven Eckelman <sven@narfation.org> Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Diffstat (limited to 'net/batman-adv')
-rw-r--r--net/batman-adv/distributed-arp-table.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index 3d21dd83f8cc..b85da4b7a77b 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -88,7 +88,7 @@ struct batadv_dhcp_packet {
__u8 sname[64];
__u8 file[128];
__be32 magic;
- __u8 options[0];
+ __u8 options[];
};
#define BATADV_DHCP_YIADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->yiaddr)