Return-path: Received: from lpdvrndsmtp01.broadcom.com ([192.19.229.170]:51629 "EHLO rnd-relay.smtp.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750892AbdGGMBh (ORCPT ); Fri, 7 Jul 2017 08:01:37 -0400 From: Arend van Spriel To: Kalle Valo Cc: Linus Torvalds , linux-wireless@vger.kernel.org, Arend van Spriel Subject: [PATCH] brcmfmac: fix possible buffer overflow in brcmf_cfg80211_mgmt_tx() Date: Fri, 7 Jul 2017 13:01:33 +0100 Message-Id: <1499428893-30750-1-git-send-email-arend.vanspriel@broadcom.com> (sfid-20170707_140140_467929_3104918C) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: The lower level nl80211 code in cfg80211 ensures that "len" is between 25 and NL80211_ATTR_FRAME (2304). We subtract DOT11_MGMT_HDR_LEN (24) from "len" so thats's max of 2280. However, the action_frame->data[] buffer is only BRCMF_FIL_ACTION_FRAME_SIZE (1800) bytes long so this memcpy() can overflow. memcpy(action_frame->data, &buf[DOT11_MGMT_HDR_LEN], le16_to_cpu(action_frame->len)); Reported-by: "freenerguo(郭大兴)" Signed-off-by: Arend van Spriel --- Hi Kalle, Here is the patch as Linus send it to us and security@kernel.org. I removed the lower bound check as that is already done in cfg80211. Now I signed off on the patch although formally I suppose Linus should sign it off. Putting it out there so people can respond as deemed necessary. Now fingers crossed whether patchwork will properly deal with the UTF-8 characters :-p Regards, Arend --- drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c index cd1d673..d182a00 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c @@ -4851,6 +4851,11 @@ static int brcmf_cfg80211_stop_ap(struct wiphy *wiphy, struct net_device *ndev) cfg80211_mgmt_tx_status(wdev, *cookie, buf, len, true, GFP_KERNEL); } else if (ieee80211_is_action(mgmt->frame_control)) { + if (len > BRCMF_FIL_ACTION_FRAME_SIZE + DOT11_MGMT_HDR_LEN) { + brcmf_err("invalid action frame length\n"); + err = -EINVAL; + goto exit; + } af_params = kzalloc(sizeof(*af_params), GFP_KERNEL); if (af_params == NULL) { brcmf_err("unable to allocate frame\n"); -- 1.9.1