staging: rtl8723bs: fix stack buffer overflow in OnAssocReq IE parsing

The Supported Rates IE length from an incoming Association Request frame
was used directly as the memcpy() length when copying into a fixed-size
16-byte stack buffer (supportRate). A malicious station can advertise an
IE length larger than 16 bytes, causing a stack buffer overflow.

Clamp ie_len to the buffer size before copying the Supported Rates IE,
and correct the bounds check when merging Extended Supported Rates to
prevent a second potential overflow.

This prevents kernel stack corruption triggered by malformed association
requests.

Signed-off-by: Navaneeth K <knavaneeth786@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: cyberkunju

drivers/staging/rtl8723bs/core/rtw_mlme_ext.c

@@ -1028,14 +1028,17 @@ unsigned int OnAssocReq(struct adapter *padapter, union recv_frame *precv_frame)
 		status = WLAN_STATUS_CHALLENGE_FAIL;
 		goto OnAssocReqFail;
 	} else {
+		if (ie_len > sizeof(supportRate))
+			ie_len = sizeof(supportRate);
+
 		memcpy(supportRate, p+2, ie_len);
 		supportRateNum = ie_len;
 
 		p = rtw_get_ie(pframe + WLAN_HDR_A3_LEN + ie_offset, WLAN_EID_EXT_SUPP_RATES, &ie_len,
 				pkt_len - WLAN_HDR_A3_LEN - ie_offset);
 		if (p) {
 
-			if (supportRateNum <= sizeof(supportRate)) {
+			if (supportRateNum + ie_len <= sizeof(supportRate)) {
 				memcpy(supportRate+supportRateNum, p+2, ie_len);
 				supportRateNum += ie_len;
 			}