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Date:   Thu, 7 Feb 2019 18:44:56 -0600
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To:     Wensong Zhang <wensong@linux-vs.org>,
        Simon Horman <horms@verge.net.au>,
        Julian Anastasov <ja@ssi.bg>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
        Florian Westphal <fw@strlen.de>,
        "David S. Miller" <davem@davemloft.net>
Cc:     netdev@vger.kernel.org, lvs-devel@vger.kernel.org,
        netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
        linux-kernel@vger.kernel.org,
        "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH net-next] ipvs: Use struct_size() helper
Message-ID: <20190208004456.GA15845@embeddedor>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
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User-Agent: Mutt/1.9.4 (2018-02-28)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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>
---
 net/netfilter/ipvs/ip_vs_ctl.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 7d6318664eb2..bcd9112f47d9 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -2734,8 +2734,7 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
 		int size;
 
 		get = (struct ip_vs_get_services *)arg;
-		size = sizeof(*get) +
-			sizeof(struct ip_vs_service_entry) * get->num_services;
+		size = struct_size(get, entrytable, get->num_services);
 		if (*len != size) {
 			pr_err("length: %u != %u\n", *len, size);
 			ret = -EINVAL;
@@ -2776,8 +2775,7 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
 		int size;
 
 		get = (struct ip_vs_get_dests *)arg;
-		size = sizeof(*get) +
-			sizeof(struct ip_vs_dest_entry) * get->num_dests;
+		size = struct_size(get, entrytable, get->num_dests);
 		if (*len != size) {
 			pr_err("length: %u != %u\n", *len, size);
 			ret = -EINVAL;
-- 
2.20.1