From: Eric Dumazet <eduma...@google.com>
Date: Wed, 1 Jul 2020 11:43:04 -0700
> My prior fix went a bit too far, according to Herbert and Mathieu.
>
> Since we accept that concurrent TCP MD5 lookups might see inconsistent
> keys, we can use READ_ONCE()/WRITE_ONCE() instead of smp_rmb()/smp_wmb()
>
> Clearing all key->key[] is needed to avoid possible KMSAN reports,
> if key->keylen is increased. Since tcp_md5_do_add() is not fast path,
> using __GFP_ZERO to clear all struct tcp_md5sig_key is simpler.
>
> data_race() was added in linux-5.8 and will prevent KCSAN reports,
> this can safely be removed in stable backports, if data_race() is
> not yet backported.
>
> v2: use data_race() both in tcp_md5_hash_key() and tcp_md5_do_add()
>
> Fixes: 6a2febec338d ("tcp: md5: add missing memory barriers in
> tcp_md5_do_add()/tcp_md5_hash_key()")
> Signed-off-by: Eric Dumazet <eduma...@google.com>
Applied and queued up for -stable, thanks Eric.
