UPSTREAM: 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.

Cc: stable@vger.kernel.org # v4.4, v4.1
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>

diff --git a/drivers/net/wireless/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/brcm80211/brcmfmac/cfg80211.c
index deb5f78dcacc0d9ef188360d300a7b4f1bcfba19..786fff3d746666ff2232fb63575c40d553ca56ae 100644 (file)
--- a/drivers/net/wireless/brcm80211/brcmfmac/cfg80211.c
+++ b/drivers/net/wireless/brcm80211/brcmfmac/cfg80211.c
@@ -4099,7 +4099,7 @@ 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);