staging: rtl8723bs: fix out-of-bounds read in OnBeacon ESR IE parsing

In the Linux kernel, the following vulnerability has been resolved: staging: rtl8723bs: fix out-of-bounds read in OnBeacon ESR IE parsing The Extended Supported Rates (ESR) IE handling in OnBeacon accessed *(p + 1 + ielen) and *(p + 2 + ielen) without verifying that these offsets lie within the received frame buffer. A malformed beacon with an ESR IE positioned at the end of the buffer could cause an out-of-bounds read, potentially triggering a kernel panic. Add a boundary check to ensure that the ESR IE body and the subsequent bytes are within the limits of the frame before attempting to access them. This prevents OOB reads caused by malformed beacon frames.