Message-ID: <75be2d3b-99c4-f84b-4da5-da0f4c220359@gmail.com>
Date:   Sat, 20 Nov 2021 16:17:33 +0100
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Subject: Re: [PATCH] mac80211: Use memset_after() to clear tx status
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To:     Kees Cook <keescook@chromium.org>,
        Johannes Berg <johannes@sipsolutions.net>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Christian Lamparter <chunkeey@googlemail.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org, linux-hardening@vger.kernel.org
References: <20211118203839.1289276-1-keescook@chromium.org>
From:   Christian Lamparter <chunkeey@gmail.com>
In-Reply-To: <20211118203839.1289276-1-keescook@chromium.org>
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Precedence: bulk

On 18/11/2021 21:38, Kees Cook wrote:
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memset(), avoid intentionally writing across
> neighboring fields.
> 
> Use memset_after() so memset() doesn't get confused about writing
> beyond the destination member that is intended to be the starting point
> of zeroing through the end of the struct.
> 
> Additionally fix the common helper, ieee80211_tx_info_clear_status(),
> which was not clearing ack_signal, but the open-coded versions
> did. Johannes Berg points out this bug was introduced by commit
> e3e1a0bcb3f1 ("mac80211: reduce IEEE80211_TX_MAX_RATES") but was harmless.
> 
> Also drops the associated unneeded BUILD_BUG_ON()s, and adds a note to
> carl9170 about usage.
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Christian Lamparter <chunkeey@gmail.com> [both CARL9170+P54USB on real HW]