From b65a2d8c8614386f7e8d38ea150749f8a862f431 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Wed, 3 Jun 2020 13:19:58 +0300
Subject: [PATCH] Staging: rtl8723bs: prevent buffer overflow in update_sta_support_rate()
Git-commit: b65a2d8c8614386f7e8d38ea150749f8a862f431
Patch-mainline: v5.8-rc3
References: git-fixes

The "ie_len" variable is in the 0-255 range and it comes from the
network.  If it's over NDIS_802_11_LENGTH_RATES_EX (16) then that will
lead to memory corruption.

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200603101958.GA1845750@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/staging/rtl8723bs/core/rtw_wlan_util.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
+++ b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
@@ -1904,12 +1904,14 @@ int update_sta_support_rate(struct adapt
 	pIE = (struct ndis_80211_var_ie *)rtw_get_ie(pvar_ie, _SUPPORTEDRATES_IE_, &ie_len, var_ie_len);
 	if (pIE == NULL)
 		return _FAIL;
+	if (ie_len > sizeof(pmlmeinfo->FW_sta_info[cam_idx].SupportedRates))
+		return _FAIL;
 
 	memcpy(pmlmeinfo->FW_sta_info[cam_idx].SupportedRates, pIE->data, ie_len);
 	supportRateNum = ie_len;
 
 	pIE = (struct ndis_80211_var_ie *)rtw_get_ie(pvar_ie, _EXT_SUPPORTEDRATES_IE_, &ie_len, var_ie_len);
-	if (pIE)
+	if (pIE && (ie_len <= sizeof(pmlmeinfo->FW_sta_info[cam_idx].SupportedRates) - supportRateNum))
 		memcpy((pmlmeinfo->FW_sta_info[cam_idx].SupportedRates + supportRateNum), pIE->data, ie_len);
 
 	return _SUCCESS;