staging: rtl8723bs: fix OOB reads in rtw_get_sec_ie(), rtw_get_wapi_ie(), and rtw_get_wps_attr()

Summary

In the Linux kernel, the following vulnerability has been resolved: staging: rtl8723bs: fix OOB reads in rtw_get_sec_ie(), rtw_get_wapi_ie(), and rtw_get_wps_attr() Three IE/attribute parsing functions have missing bounds checks. rtw_get_sec_ie() and rtw_get_wapi_ie() iterate over a raw IE buffer without verifying that the header bytes (tag + length) are within the remaining buffer before reading them. Additionally, rtw_get_sec_ie() compares the 4-byte WPA OUI at cnt+2 without checking that at least 6 bytes remain, and rtw_get_wapi_ie() compares a 4-byte WAPI OUI at cnt+6 without checking that at least 10 bytes remain. rtw_get_wps_attr() reads wps_ie[0] and wps_ie+2 unconditionally at entry, before verifying that wps_ielen is large enough to contain the 6-byte WPS IE header (element_id + length + 4-byte OUI). Inside the attribute loop, get_unaligned_be16() is called on attr_ptr and attr_ptr+2 without checking that 4 bytes remain in the buffer. Add a cnt+2 bounds check before each loop body in rtw_get_sec_ie() and rtw_get_wapi_ie(), guard each multi-byte comparison with a minimum IE length requirement, add a wps_ielen < 6 early return in rtw_get_wps_attr(), and add a 4-byte bounds check in its inner loop.