Re: [PATCH] mac80211: Use memset_after() to clear tx status

[Christian Lamparter]

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@xxxxxxxxxxxx>
Tested-by: Christian Lamparter <chunkeey@xxxxxxxxx> [both CARL9170+P54USB on real HW]