nl80211: Use struct_size() in kzalloc()

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 = kzalloc(size, GFP_KERNEL)

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL)

Notice that, in this case, variable size_of_regd 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: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index e7984f025bc73703bc913d466ae826fb776f2d46..64f191244c678ff47eb5c4ebef695e3acf273e88 100644 (file)
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3876,8 +3876,7 @@ static struct cfg80211_acl_data *parse_acl_data(struct wiphy *wiphy,
        if (n_entries > wiphy->max_acl_mac_addrs)
                return ERR_PTR(-ENOTSUPP);
 
-       acl = kzalloc(sizeof(*acl) + (sizeof(struct mac_address) * n_entries),
-                     GFP_KERNEL);
+       acl = kzalloc(struct_size(acl, mac_addrs, n_entries), GFP_KERNEL);
        if (!acl)
                return ERR_PTR(-ENOMEM);
 
@@ -6916,7 +6915,7 @@ static int nl80211_set_reg(struct sk_buff *skb, struct genl_info *info)
        struct nlattr *nl_reg_rule;
        char *alpha2;
        int rem_reg_rules, r;
-       u32 num_rules = 0, rule_idx = 0, size_of_regd;
+       u32 num_rules = 0, rule_idx = 0;
        enum nl80211_dfs_regions dfs_region = NL80211_DFS_UNSET;
        struct ieee80211_regdomain *rd;
 
@@ -6941,10 +6940,7 @@ static int nl80211_set_reg(struct sk_buff *skb, struct genl_info *info)
        if (!reg_is_valid_request(alpha2))
                return -EINVAL;
 
-       size_of_regd = sizeof(struct ieee80211_regdomain) +
-                      num_rules * sizeof(struct ieee80211_reg_rule);
-
-       rd = kzalloc(size_of_regd, GFP_KERNEL);
+       rd = kzalloc(struct_size(rd, reg_rules, num_rules), GFP_KERNEL);
        if (!rd)
                return -ENOMEM;