wifi: wilc1000: validate assoc response length before subtracting header

Summary

In the Linux kernel, the following vulnerability has been resolved: wifi: wilc1000: validate assoc response length before subtracting header wilc_parse_assoc_resp_info() computes the trailing IE length as ies_len = buffer_len - sizeof(*res); without first checking that buffer_len is at least sizeof(struct wilc_assoc_resp) (6 bytes). buffer_len is the length reported for a received association response (host_int_parse_assoc_resp_info() passes hif_drv->assoc_resp / assoc_resp_info_len straight in) and must be validated before the driver accesses the fixed header. For a frame shorter than the 6-byte fixed header, the subtraction wraps. For a four-byte response the result is truncated to a u16 ies_len of 65534, so kmemdup() then attempts to copy 65534 bytes starting at buffer + sizeof(*res), beyond the valid association-response data (CWE-125). A response shorter than four bytes can also cause an out-of-bounds read of res->status_code at offsets 2 and 3. Reject frames too short to hold the fixed header before touching the header or computing ies_len. Also set the connection status to a failure on this path: the caller falls through to a "conn_info->status == WLAN_STATUS_SUCCESS" check after the parser returns, so leaving the status untouched could let a malformed short response be treated as a successful association.