Return-path: Received: from mail-pf0-f195.google.com ([209.85.192.195]:36276 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752916AbcGSQmO (ORCPT ); Tue, 19 Jul 2016 12:42:14 -0400 Received: by mail-pf0-f195.google.com with SMTP id y134so1683657pfg.3 for ; Tue, 19 Jul 2016 09:42:14 -0700 (PDT) Subject: Re: [PATCH 3/4] brcmsmac: Fix invalid memcpy() size in brcms_c_d11hdrs_mac80211 To: Arend Van Spriel , brcm80211-dev-list.pdl@broadcom.com References: <1468884277-18606-1-git-send-email-f.fainelli@gmail.com> <1468884277-18606-4-git-send-email-f.fainelli@gmail.com> <685abc5d-2e3d-cdce-4849-f7e5beb3309d@broadcom.com> Cc: linux-wireless@vger.kernel.org, pieterpg@broadcom.com, kvalo@codeaurora.org, hante.meuleman@broadcom.com From: Florian Fainelli Message-ID: <578E5864.3040309@gmail.com> (sfid-20160719_184218_083865_6877485A) Date: Tue, 19 Jul 2016 09:42:12 -0700 MIME-Version: 1.0 In-Reply-To: <685abc5d-2e3d-cdce-4849-f7e5beb3309d@broadcom.com> Content-Type: text/plain; charset=utf-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 07/19/2016 03:38 AM, Arend Van Spriel wrote: > On 19-7-2016 1:24, Florian Fainelli wrote: >> struct ieee80211_rts::ra is only ETH_ALEN wide, yet we attempt to copy 2 >> * ETH_ALEN, which will potentially overrun the destination buffer. > > NACK - this is intentional. Have to admit it is a bit of trickery. This seems fragile, if there is any kind of re-ordering of fields within that structure your trick breaks apart. > struct ieee80211_rts is mapped over struct d11txh which is sent to > hardware. The struct is used for both RTS and CTS. Transmitting CTS will > only fill 802.11 addr2 in struct ieee80211_rts::ra. Transmitting RTS > fills 802.11 addr1 in ra and 802.11 addr2 in ta using single memcpy(). > Not very clear, but your change is not the way to go here. Fair enough, as Kalle suggested, this deserves a comment explaining why, I would not be surprised other people would trip over that. > > Regards, > Arend > >> Reported-by: coverity (CID 145657) >> Fixes: 5b435de0d7868 ("net: wireless: add brcm80211 drivers") >> Signed-off-by: Florian Fainelli >> --- >> drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c b/drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c >> index c2a938b59044..59813a3666eb 100644 >> --- a/drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c >> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c >> @@ -6671,7 +6671,7 @@ brcms_c_d11hdrs_mac80211(struct brcms_c_info *wlc, struct ieee80211_hw *hw, >> rts->frame_control = cpu_to_le16(IEEE80211_FTYPE_CTL | >> IEEE80211_STYPE_RTS); >> >> - memcpy(&rts->ra, &h->addr1, 2 * ETH_ALEN); >> + memcpy(&rts->ra, &h->addr1, ETH_ALEN); >> } >> >> /* mainrate >> -- Florian