On Wed, Jul 01, 2020 at 11:43:04AM -0700, Eric Dumazet wrote:
> 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>
> Cc: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
> Cc: Herbert Xu <herb...@gondor.apana.org.au>
> Cc: Marco Elver <el...@google.com>
> ---
> net/ipv4/tcp.c | 8 ++++----
> net/ipv4/tcp_ipv4.c | 19 ++++++++++++++-----
> 2 files changed, 18 insertions(+), 9 deletions(-)
Acked-by: Herbert Xu <herb...@gondor.apana.org.au>
Thanks,
--
Email: Herbert Xu <herb...@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
