net/sched: 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);
instance = alloc(size, GFP_KERNEL)

This code was detected with the help of Coccinelle.

---
 net/sched/act_pedit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 2b372a06b432..3663d3b615a4 100644
@@ -406,7 +406,7 @@ static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
 	struct tcf_t t;
 	int s;
 
-	s = sizeof(*opt) + p->tcfp_nkeys * sizeof(struct tc_pedit_key);
+	s = struct_size(opt, keys, p->tcfp_nkeys);
 
 	/* netlink spinlocks held above us - must use ATOMIC */
 	opt = kzalloc(s, GFP_ATOMIC);

2.20.1

From: "Gustavo A. R. Silva" <[email protected]>
Date: Thu, 7 Feb 2019 19:02:52 -0600

Applied.