[PATCH 1/2] staging: rtl8723bs: fix OOB write in HT_caps_handler()

[Alexandru Hossu <hossu.alexandru@gmail.com>]

From: Alexandru Hossu <a.hossu@student.tudelft.nl>

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.

The parallel function HT_info_handler() already carries the correct guard:

  if (pIE->length > sizeof(struct HT_info_element))
          return;

Apply the same pattern to HT_caps_handler().

Signed-off-by: Alexandru Hossu <a.hossu@student.tudelft.nl>
---
 drivers/staging/rtl8723bs/core/rtw_wlan_util.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
index 6a7c09db4..b75e7f4f8 100644
--- a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
+++ b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
@@ -934,6 +934,9 @@ void HT_caps_handler(struct adapter *padapter, struct ndis_80211_var_ie *pIE)
 	if (phtpriv->ht_option == false)
 		return;
 
+	if (pIE->length > sizeof(struct HT_caps_element))
+		return;
+
 	pmlmeinfo->HT_caps_enable = 1;
 
 	for (i = 0; i < (pIE->length); i++) {
-- 
2.53.0