brcmfmac: avoid potential stack overflow in brcmf_cfg80211_start_ap()

commit ded89912156b1a47d940a0c954c43afbabd0c42c upstream.

User-space can choose to omit NL80211_ATTR_SSID and only provide raw
IE TLV data. When doing so it can provide SSID IE with length exceeding
the allowed size. The driver further processes this IE copying it
into a local variable without checking the length. Hence stack can be
corrupted and used as exploit.

Reported-by: Daxing Guo <freener.gdx@gmail.com>
Reviewed-by: Hante Meuleman <hante.meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
Reviewed-by: Franky Lin <franky.lin@broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c b/drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c
index 301e572e89233649b5af905c7e965b27222d6490..2c524305589fb6cc8ad25aab46a151a13544b455 100644 (file)
--- a/drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c
+++ b/drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c
@@ -3726,7 +3726,7 @@ brcmf_cfg80211_start_ap(struct wiphy *wiphy, struct net_device *ndev,
                                (u8 *)&settings->beacon.head[ie_offset],
                                settings->beacon.head_len - ie_offset,
                                WLAN_EID_SSID);
-               if (!ssid_ie)
+               if (!ssid_ie || ssid_ie->len > IEEE80211_MAX_SSID_LEN)
                        return -EINVAL;
 
                memcpy(ssid_le.SSID, ssid_ie->data, ssid_ie->len);