[lvc-project] [PATCH 5.10] staging: rtl8723bs: fix OOB write in HT_caps_handler()

[Mikhail Dmitrichenko]

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

commit f8001e1a516ba3b495728c65b61f799cbfad6bd0 upstream.

HT_caps_handler() iterates pIE->length bytes and writes into
HT_caps.u.HT_cap[], which is a fixed 26-byte array (sizeof struct
HT_caps_element). Because pIE->length is a raw u8 from an over-the-air
802.11 AssocResponse frame and is never validated, a malicious AP can
set it up to 255, causing up to 229 bytes of out-of-bounds writes into
adjacent fields of struct mlme_ext_info.

Truncate the iteration count to the size of HT_caps.u.HT_cap using
umin() so that data from a longer-than-expected IE is silently ignored
rather than written out of bounds, preserving interoperability with APs
that pad the element. An early return on oversized IEs was considered
but rejected: it would bypass the pmlmeinfo->HT_caps_enable = 1
assignment that precedes the loop, silently disabling HT mode for APs
that append extra bytes to the HT Capabilities IE.

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
Cc: stable <stable at kernel.org>
Signed-off-by: Alexandru Hossu <hossu.alexandru at gmail.com>
Reviewed-by: Luka Gejak <luka.gejak at linux.dev>
Link: https://patch.msgid.link/20260522004531.1038924-5-hossu.alexandru@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
[ mdmitrichenko: adapt to 5.10: struct ndis_80211_var_ie still has the
  CamelCase Length field here, so use pIE->Length instead of pIE->length. ]
Signed-off-by: Mikhail Dmitrichenko <mdmitrichenko at astralinux.ru>
---
Backport fix for CVE-2026-64440
 drivers/staging/rtl8723bs/core/rtw_wlan_util.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
index 4881adf930ab..62aafe7e885b 100644
--- a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
+++ b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
@@ -1029,7 +1029,8 @@ void HT_caps_handler(struct adapter *padapter, struct ndis_80211_var_ie *pIE)
 
 	pmlmeinfo->HT_caps_enable = 1;
 
-	for (i = 0; i < (pIE->Length); i++) {
+	for (i = 0; i < umin(pIE->Length,
+			     sizeof(pmlmeinfo->HT_caps.u.HT_cap)); i++) {
 		if (i != 2) {
 			/* 	Commented by Albert 2010/07/12 */
 			/* 	Got the endian issue here. */
-- 
2.43.0