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Message-ID: <347234b097eb93a0882ad2a3a209c2b7923ff611.camel@sipsolutions.net>
Subject: Re: [PATCH 39/64] mac80211: Use memset_after() to clear tx status
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Kees Cook <keescook@chromium.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>
Cc:     "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Keith Packard <keithpac@amazon.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-staging@lists.linux.dev, linux-block@vger.kernel.org,
        linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com,
        linux-hardening@vger.kernel.org
Date:   Fri, 13 Aug 2021 09:41:40 +0200
In-Reply-To: <202107310852.551B66EE32@keescook>
References: <20210727205855.411487-1-keescook@chromium.org>
         <20210727205855.411487-40-keescook@chromium.org>
         <202107310852.551B66EE32@keescook>
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On Sat, 2021-07-31 at 08:55 -0700, Kees Cook wrote:
> 
> > @@ -278,9 +278,7 @@ static void carl9170_tx_release(struct kref *ref)
> >  	BUILD_BUG_ON(
> >  	    offsetof(struct ieee80211_tx_info, status.ack_signal) != 20);
> >  
> > 
> > -	memset(&txinfo->status.ack_signal, 0,
> > -	       sizeof(struct ieee80211_tx_info) -
> > -	       offsetof(struct ieee80211_tx_info, status.ack_signal));
> > +	memset_after(&txinfo->status, 0, rates);

FWIW, I think we should also remove the BUILD_BUG_ON() now in all the
places - that was meant to give people a hint to update if some field
ordering etc. changed, but now that it's "after rates" this is no longer
necessary.

johannes