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netfilter: xt_recent: Use struct_size() in kvzalloc()

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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
removed.

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>
This commit is contained in:
Gustavo A. R. Silva 2019-02-07 18:56:08 -06:00 committed by Pablo Neira Ayuso
parent 6fde9df6b7
commit 6ca64ef37d
1 changed files with 1 additions and 3 deletions
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4
net/netfilter/xt_recent.c
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@ -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;