[07/11] netfilter: xt_recent: Use struct_size() in kvzalloc()
diff mbox series

Message ID 20190217232357.29858-8-pablo@netfilter.org
State Accepted
Delegated to: David Miller
Headers show
  • [01/11] netfilter: nf_tables: add NFTA_RULE_POSITION_ID to nla_policy
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Commit Message

Pablo Neira Ayuso Feb. 17, 2019, 11:23 p.m. UTC
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>

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;
    void *entry[];

size = sizeof(struct foo) + count * sizeof(void *);
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)

Notice that, in this case, variable sz is not necessary, hence it is

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
 net/netfilter/xt_recent.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff mbox series

diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
index f44de4bc2100..1664d2ec8b2f 100644
--- a/net/netfilter/xt_recent.c
+++ b/net/netfilter/xt_recent.c
@@ -337,7 +337,6 @@  static int recent_mt_check(const struct xt_mtchk_param *par,
 	unsigned int nstamp_mask;
 	unsigned int i;
 	int ret = -EINVAL;
-	size_t sz;
 	net_get_random_once(&hash_rnd, sizeof(hash_rnd));
@@ -387,8 +386,7 @@  static int recent_mt_check(const struct xt_mtchk_param *par,
 		goto out;
-	sz = sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size;
-	t = kvzalloc(sz, GFP_KERNEL);
+	t = kvzalloc(struct_size(t, iphash, ip_list_hash_size), GFP_KERNEL);
 	if (t == NULL) {
 		ret = -ENOMEM;
 		goto out;