From 6e68f499e93429e521af40cb25129f27c6c80a10 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 2 Mar 2020 06:06:07 -0600 Subject: net: ip6_fib: 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 Signed-off-by: David S. Miller --- include/net/ip6_fib.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/net/ip6_fib.h') diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h index fd60a8ac02ee..6ec26e4d7f11 100644 --- a/include/net/ip6_fib.h +++ b/include/net/ip6_fib.h @@ -198,7 +198,7 @@ struct fib6_info { struct rcu_head rcu; struct nexthop *nh; - struct fib6_nh fib6_nh[0]; + struct fib6_nh fib6_nh[]; }; struct rt6_info { -- cgit