wifi: libipw: reject too-short association responses

In the Linux kernel, the following vulnerability has been resolved: wifi: libipw: reject too-short association responses libipw_handle_assoc_resp() reads the capability, status and aid fields of the 30-byte association response prefix and then computes the information element length as stats->len - sizeof(*frame) stats->len is a u16 and sizeof() has type size_t, so the subtraction is evaluated as size_t and wraps instead of going negative. Truncating that to the u16 length parameter of libipw_parse_info_param() turns a frame shorter than the fixed fields into a length near 64 KiB, and the parser then reads past the receive buffer. Both the ipw2100 and ipw2200 management receive paths reach this function having established only that the frame carries the generic 24-byte three-address header. Reject the frame before any fixed field is touched. Found by an AI-assisted review of length arithmetic in management frame parsers. Verified with a KUnit case under Generic KASAN on arm64 under QEMU; I do not have the hardware, so it is not tested on a real device.