In api "__wlan_hdd_cfg80211_vendor_scan", the ssid length is u8,
when memcpy is done for ssid, the length is not validated and
nla_len(attr) is used directly in memcpy which can result in buffer
overwrite.
Add a check to validate the max length of scan ssid against
SIR_MAC_MAX_SSID_LENGTH.
Change-Id: If4c25710973ee50094c5d52410269962f552ac3f
CRs-Fixed: 2153326