[ovs-dev] [PATCH v1 3/9] conntrack: Init hash basis first at creation

[William Tu]

On Wed, Feb 17, 2021 at 8:34 AM Gaetan Rivet <grive at u256.net> wrote:
>
> The 'hash_basis' field is used sometimes during sub-systems init
> routine. It will be 0 by default before randomization. Sub-systems would
> then init some nodes with incorrect hash values.
>
> The timeout policies module is affected, making the default policy being
> referenced using an incorrect hash value.
>
> Fixes: 2078901a4c14 ("userspace: Add conntrack timeout policy support.")
> Signed-off-by: Gaetan Rivet <grive at u256.net>
> Reviewed-by: Eli Britstein <elibr at nvidia.com>
> ---

LGTM, thanks for the fix.
Acked-by: William Tu <u9012063 at gmail.com>


>  lib/conntrack.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/lib/conntrack.c b/lib/conntrack.c
> index c218200dc..8062dcd6b 100644
> --- a/lib/conntrack.c
> +++ b/lib/conntrack.c
> @@ -291,6 +291,11 @@ conntrack_init(void)
>      static struct ovsthread_once setup_l4_once = OVSTHREAD_ONCE_INITIALIZER;
>      struct conntrack *ct = xzalloc(sizeof *ct);
>
> +    /* This value can be used during init (e.g. timeout_policy_init()),
> +     * set it first to ensure it is available.
> +     */
> +    ct->hash_basis = random_uint32();
> +
>      ovs_rwlock_init(&ct->resources_lock);
>      ovs_rwlock_wrlock(&ct->resources_lock);
>      hmap_init(&ct->alg_expectations);
> @@ -308,7 +313,6 @@ conntrack_init(void)
>      timeout_policy_init(ct);
>      ovs_mutex_unlock(&ct->ct_lock);
>
> -    ct->hash_basis = random_uint32();
>      atomic_count_init(&ct->n_conn, 0);
>      atomic_init(&ct->n_conn_limit, DEFAULT_N_CONN_LIMIT);
>      atomic_init(&ct->tcp_seq_chk, true);
> --
> 2.30.0
>