[PATCH net-next] net/sched: use struct_size() helper

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Jamal Hadi Salim <jhs@mojatatu.com>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Jiri Pirko <jiri@resnulli.us>,
	"David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH net-next] net/sched: use struct_size() helper
Date: Thu, 7 Feb 2019 19:02:52 -0600	[thread overview]
Message-ID: <20190208010252.GA24824@embeddedor> (raw)

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.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 net/sched/act_pedit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/act_pedit.c b/net/sched/act_pedit.c
index 2b372a06b432..3663d3b615a4 100644
--- a/net/sched/act_pedit.c
+++ b/net/sched/act_pedit.c
@@ -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

