[PATCH 4.19 123/131] Staging: rtl8723bs: prevent buffer overflow in update_sta_support_rate()

[Sasha Levin]

From: Dan Carpenter <dan.carpen...@oracle.com>

commit b65a2d8c8614386f7e8d38ea150749f8a862f431 upstream.

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.carpen...@oracle.com>
Cc: stable <sta...@vger.kernel.org>
Link: https://lore.kernel.org/r/20200603101958.GA1845750@mwanda
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/staging/rtl8723bs/core/rtw_wlan_util.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c 
b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
index 2c65af319a604..6c6bf03ac38aa 100644
--- a/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
+++ b/drivers/staging/rtl8723bs/core/rtw_wlan_util.c
@@ -1856,12 +1856,14 @@ int update_sta_support_rate(struct adapter *padapter, 
u8 *pvar_ie, uint var_ie_l
        pIE = (struct ndis_80211_var_ie *)rtw_get_ie(pvar_ie, 
_SUPPORTEDRATES_IE_, &ie_len, var_ie_len);
        if (!pIE)
                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;
-- 
2.25.1