wifi: mwifiex: validate scan response extents

In the Linux kernel, the following vulnerability has been resolved: wifi: mwifiex: validate scan response extents mwifiex_ret_802_11_scan() subtracts the fixed response fields and the firmware-provided BSS length from resp->size without first proving that either extent fits. A short response or oversized BSS length can therefore underflow tlv_buf_size and make the TLV parser walk beyond the command response. Compute the fixed extent from the selected normal or background scan response. Validate that the fixed fields and BSS data fit before deriving the TLV extent and entering the parser.

Where it's fixed