staging: rtl8723bs: fix OOB read in update_beacon_info() IE loop

The IE parsing loop in update_beacon_info() advances by
(pIE->length + 2) each iteration but only guards on i < len.
When a malicious AP sends a Beacon whose last IE has only one byte
remaining in the frame (the element_id byte lands at len-1), the loop
reads pIE->length from one byte past the allocated receive buffer.

Additionally, even when the header bytes are in bounds, pIE->length
itself can extend the data window beyond len, passing a truncated IE
to the handler functions.

Add two guards at the top of the loop body:
  1. Break if fewer than sizeof(*pIE) bytes remain (can't read header).
  2. Break if the IE's declared data extends past len.

Also replace i += (pIE->length + 2) with i += sizeof(*pIE) + pIE->length
for consistency with the sizeof(*pIE) guards added above.

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
Cc: stable <stable@kernel.org>
Reviewed-by: Luka Gejak <luka.gejak@linux.dev>
Signed-off-by: Alexandru Hossu <hossu.alexandru@gmail.com>
Link: https://patch.msgid.link/20260522004531.1038924-2-hossu.alexandru@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
index 1d37c2d5b10d9b654203146439db0a76fd5b54e3..b355d8a3ceabcb9c9ce0a187a335cc71969c164d 100644 (file)
--- a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
+++ b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
@@ -1262,7 +1262,11 @@ void update_beacon_info(struct adapter *padapter, u8 *pframe, uint pkt_len, stru
        len = pkt_len - (_BEACON_IE_OFFSET_ + WLAN_HDR_A3_LEN);
 
        for (i = 0; i < len;) {
+               if (i + sizeof(*pIE) > len)
+                       break;
                pIE = (struct ndis_80211_var_ie *)(pframe + (_BEACON_IE_OFFSET_ + WLAN_HDR_A3_LEN) + i);
+               if (i + sizeof(*pIE) + pIE->length > len)
+                       break;
 
                switch (pIE->element_id) {
                case WLAN_EID_VENDOR_SPECIFIC:
@@ -1287,7 +1291,7 @@ void update_beacon_info(struct adapter *padapter, u8 *pframe, uint pkt_len, stru
                        break;
                }
 
-               i += (pIE->length + 2);
+               i += sizeof(*pIE) + pIE->length;
        }
 }