[PATCH][next] Bluetooth: a2mp: Use struct_size() helper

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Marcel Holtmann <marcel@holtmann.org>,
	Johan Hedberg <johan.hedberg@gmail.com>,
	"David S. Miller" <davem@davemloft.net>
Cc: linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH][next] Bluetooth: a2mp: Use struct_size() helper
Date: Thu, 7 Feb 2019 18:28:17 -0600	[thread overview]
Message-ID: <20190208002817.GA15338@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/bluetooth/a2mp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bluetooth/a2mp.c b/net/bluetooth/a2mp.c
index 58fc6333d412..5f918ea18b5a 100644
--- a/net/bluetooth/a2mp.c
+++ b/net/bluetooth/a2mp.c
@@ -174,7 +174,7 @@ static int a2mp_discover_req(struct amp_mgr *mgr, struct sk_buff *skb,
 			num_ctrl++;
 	}
 
-	len = num_ctrl * sizeof(struct a2mp_cl) + sizeof(*rsp);
+	len = struct_size(rsp, cl, num_ctrl);
 	rsp = kmalloc(len, GFP_ATOMIC);
 	if (!rsp) {
 		read_unlock(&hci_dev_list_lock);
-- 
2.20.1

