[PATCH 5.10.y 10/10] staging: rtl8723bs: fix OOB read in update_beacon_info() IE loop

[Sasha Levin <sashal@kernel.org>]

From: Alexandru Hossu <hossu.alexandru@gmail.com>

[ Upstream commit ed51de4a86e173c3b0ef78e039c2e49e08b11f16 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/staging/rtl8723bs/core/rtw_wlan_util.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
index aa02881f4efe59..7d5fe15379dc83 100644
--- a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
+++ b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
@@ -1389,7 +1389,11 @@ 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 _VENDOR_SPECIFIC_IE_:
@@ -1414,7 +1418,7 @@ void update_beacon_info(struct adapter *padapter, u8 *pframe, uint pkt_len, stru
 			break;
 		}
 
-		i += (pIE->length + 2);
+		i += sizeof(*pIE) + pIE->length;
 	}
 }
 
-- 
2.53.0