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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-02-29 03:53:11 +0300
committerDavid S. Miller <davem@davemloft.net>2020-03-01 08:52:20 +0300
commit53e76f4824f0a501353e0da3f9506542d137b634 (patch)
tree8078c56b81decfd54c10952bf16dda82b7c5b2cd
parentc61a2a76e5da267d8f5070a34c074d104155c0f6 (diff)
downloadlinux-53e76f4824f0a501353e0da3f9506542d137b634.tar.xz
ndisc: 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>
-rw-r--r--include/net/ndisc.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index b5ebeb3b0de0..1c61aeb3a1c0 100644
--- a/include/net/ndisc.h
+++ b/include/net/ndisc.h
@@ -80,12 +80,12 @@ extern struct neigh_table nd_tbl;
struct nd_msg {
struct icmp6hdr icmph;
struct in6_addr target;
- __u8 opt[0];
+ __u8 opt[];
};
struct rs_msg {
struct icmp6hdr icmph;
- __u8 opt[0];
+ __u8 opt[];
};
struct ra_msg {
@@ -98,7 +98,7 @@ struct rd_msg {
struct icmp6hdr icmph;
struct in6_addr target;
struct in6_addr dest;
- __u8 opt[0];
+ __u8 opt[];
};
struct nd_opt_hdr {