bridge: use struct_size() helper

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
    int stuff;
    struct boo entry[];
};

size = sizeof(struct foo) + count * sizeof(struct boo);
instance = alloc(size, GFP_KERNEL)

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

size = struct_size(instance, entry, count);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 1fb885a..4a048fd 100644 (file)
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1018,8 +1018,7 @@ static int br_ip6_multicast_mld2_report(struct net_bridge *br,
                if (!nsrcs)
                        return -EINVAL;
 
-               grec_len = sizeof(*grec) +
-                          sizeof(struct in6_addr) * ntohs(*nsrcs);
+               grec_len = struct_size(grec, grec_src, ntohs(*nsrcs));
 
                if (!ipv6_mc_may_pull(skb, len + grec_len))
                        return -EINVAL;