wifi: brcmfmac: Use struct_size() and array_size() in code ralated to struct brcmf_gscan_config

Prefer struct_size() over open-coded versions of idiom:

sizeof(struct-with-flex-array) + sizeof(typeof-flex-array-elements) * count

where count is the max number of items the flexible array is supposed to
contain.

Also, use array_size() in call to memcpy().

Link: https://github.com/KSPP/linux/issues/160Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/de0226a549c8d000d8974e207ede786220a3df1a.1668466470.git.gustavoars@kernel.org

drivers/net/wireless/broadcom/brcm80211/brcmfmac/pno.c

@@ -405,7 +405,7 @@ static int brcmf_pno_config_sched_scans(struct brcmf_if *ifp)
 	if (n_buckets < 0)
 		return n_buckets;
 
-	gsz = sizeof(*gscan_cfg) + n_buckets * sizeof(*buckets);
+	gsz = struct_size(gscan_cfg, bucket, n_buckets);
 	gscan_cfg = kzalloc(gsz, GFP_KERNEL);
 	if (!gscan_cfg) {
 		err = -ENOMEM;
@@ -434,8 +434,8 @@ static int brcmf_pno_config_sched_scans(struct brcmf_if *ifp)
 	gscan_cfg->flags = BRCMF_GSCAN_CFG_ALL_BUCKETS_IN_1ST_SCAN;
 
 	gscan_cfg->count_of_channel_buckets = n_buckets;
-	memcpy(&gscan_cfg->bucket[0], buckets,
-	       n_buckets * sizeof(*buckets));
+	memcpy(gscan_cfg->bucket, buckets,
+	       array_size(n_buckets, sizeof(*buckets)));
 
 	err = brcmf_fil_iovar_data_set(ifp, "pfn_gscan_cfg", gscan_cfg, gsz);