staging: rtl8188eu: fix potential memory corruption in rtw_check_beacon_data()

BugLink: https://bugs.launchpad.net/bugs/1919492
commit d4ac640322b06095128a5c45ba4a1e80929fe7f3 upstream.

The "ie_len" is a value in the 1-255 range that comes from the user.  We
have to cap it to ensure that it's not too large or it could lead to
memory corruption.

Fixes: 9a7fe54ddc3a ("staging: r8188eu: Add source files for new driver - part 1")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/YEHyQCrFZKTXyT7J@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/drivers/staging/rtl8188eu/core/rtw_ap.c b/drivers/staging/rtl8188eu/core/rtw_ap.c
index fa1e34a0d456182d83cd7bd48f601a35a257b60b..182bb944c9b3b0ba50cc2b1527ef3705c6e887b2 100644 (file)
--- a/drivers/staging/rtl8188eu/core/rtw_ap.c
+++ b/drivers/staging/rtl8188eu/core/rtw_ap.c
@@ -791,6 +791,7 @@ int rtw_check_beacon_data(struct adapter *padapter, u8 *pbuf,  int len)
        p = rtw_get_ie(ie + _BEACON_IE_OFFSET_, WLAN_EID_SSID, &ie_len,
                       pbss_network->ie_length - _BEACON_IE_OFFSET_);
        if (p && ie_len > 0) {
+               ie_len = min_t(int, ie_len, sizeof(pbss_network->ssid.ssid));
                memset(&pbss_network->ssid, 0, sizeof(struct ndis_802_11_ssid));
                memcpy(pbss_network->ssid.ssid, p + 2, ie_len);
                pbss_network->ssid.ssid_length = ie_len;
@@ -811,6 +812,7 @@ int rtw_check_beacon_data(struct adapter *padapter, u8 *pbuf,  int len)
        p = rtw_get_ie(ie + _BEACON_IE_OFFSET_, WLAN_EID_SUPP_RATES, &ie_len,
                       pbss_network->ie_length - _BEACON_IE_OFFSET_);
        if (p) {
+               ie_len = min_t(int, ie_len, NDIS_802_11_LENGTH_RATES_EX);
                memcpy(supportRate, p + 2, ie_len);
                supportRateNum = ie_len;
        }
@@ -819,6 +821,8 @@ int rtw_check_beacon_data(struct adapter *padapter, u8 *pbuf,  int len)
        p = rtw_get_ie(ie + _BEACON_IE_OFFSET_, WLAN_EID_EXT_SUPP_RATES,
                       &ie_len, pbss_network->ie_length - _BEACON_IE_OFFSET_);
        if (p) {
+               ie_len = min_t(int, ie_len,
+                              NDIS_802_11_LENGTH_RATES_EX - supportRateNum);
                memcpy(supportRate + supportRateNum, p + 2, ie_len);
                supportRateNum += ie_len;
        }
@@ -934,6 +938,7 @@ int rtw_check_beacon_data(struct adapter *padapter, u8 *pbuf,  int len)
 
                pht_cap->mcs.rx_mask[0] = 0xff;
                pht_cap->mcs.rx_mask[1] = 0x0;
+               ie_len = min_t(int, ie_len, sizeof(pmlmepriv->htpriv.ht_cap));
                memcpy(&pmlmepriv->htpriv.ht_cap, p + 2, ie_len);
        }