wifi: mac80211_hwsim: reject undersized HWSIM_ATTR_TX_INFO

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211_hwsim: reject undersized HWSIM_ATTR_TX_INFO hwsim_tx_info_frame_received_nl() casts the HWSIM_ATTR_TX_INFO payload to a struct hwsim_tx_rate * and unconditionally reads IEEE80211_TX_MAX_RATES entries (8 bytes) from it. The policy only bounds the attribute from above (NLA_BINARY .len is a maximum) and the op sets GENL_DONT_VALIDATE_STRICT, so a short or zero-length attribute is accepted and the loop reads past the payload. Require the exact length in the policy, so a malformed attribute is rejected before the handler runs.