diff options
| author | Kyle Evans <kevans@FreeBSD.org> | 2024-03-15 01:19:18 +0000 |
|---|---|---|
| committer | Kyle Evans <kevans@FreeBSD.org> | 2024-03-22 15:21:39 +0000 |
| commit | 590e02d3c088b220c19d53ce40a5aecc6fa099e4 (patch) | |
| tree | 1e72e99849c53ded6315d6501f474221f0c20572 | |
| parent | 95a7c6f18a6a28cf866384ff60b587ec30be1cd1 (diff) | |
if_wg: use proper barriers around pkt->p_state
Without appropriate load-synchronization to pair with store barriers in
wg_encrypt() and wg_decrypt(), the compiler and hardware are often
allowed to reorder these loads in wg_deliver_out() and wg_deliver_in()
such that we end up with a garbage or intermediate mbuf that we try to
pass on. The issue is particularly prevalent with the weaker
memory models of !x86 platforms.
Switch from the big-hammer wmb() to more explicit acq/rel atomics to
both make it obvious what we're syncing up with, and to avoid somewhat
hefty fences on platforms that don't necessarily need this.
With this patch, my dual-iperf3 reproducer is dramatically more stable
than it is without on aarch64.
PR: 264115
Reviewed by: andrew, zlei
(cherry picked from commit 3705d679a6344c957cae7a1b6372a8bfb8c44f0e)
| -rw-r--r-- | sys/dev/wg/if_wg.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/sys/dev/wg/if_wg.c b/sys/dev/wg/if_wg.c index c324b5fb048b..25fa53c2e672 100644 --- a/sys/dev/wg/if_wg.c +++ b/sys/dev/wg/if_wg.c @@ -1515,8 +1515,7 @@ wg_encrypt(struct wg_softc *sc, struct wg_packet *pkt) state = WG_PACKET_CRYPTED; out: pkt->p_mbuf = m; - wmb(); - pkt->p_state = state; + atomic_store_rel_int(&pkt->p_state, state); GROUPTASK_ENQUEUE(&peer->p_send); noise_remote_put(remote); } @@ -1588,8 +1587,7 @@ wg_decrypt(struct wg_softc *sc, struct wg_packet *pkt) state = WG_PACKET_CRYPTED; out: pkt->p_mbuf = m; - wmb(); - pkt->p_state = state; + atomic_store_rel_int(&pkt->p_state, state); GROUPTASK_ENQUEUE(&peer->p_recv); noise_remote_put(remote); } @@ -1645,7 +1643,7 @@ wg_deliver_out(struct wg_peer *peer) wg_peer_get_endpoint(peer, &endpoint); while ((pkt = wg_queue_dequeue_serial(&peer->p_encrypt_serial)) != NULL) { - if (pkt->p_state != WG_PACKET_CRYPTED) + if (atomic_load_acq_int(&pkt->p_state) != WG_PACKET_CRYPTED) goto error; m = pkt->p_mbuf; @@ -1687,7 +1685,7 @@ wg_deliver_in(struct wg_peer *peer) struct epoch_tracker et; while ((pkt = wg_queue_dequeue_serial(&peer->p_decrypt_serial)) != NULL) { - if (pkt->p_state != WG_PACKET_CRYPTED) + if (atomic_load_acq_int(&pkt->p_state) != WG_PACKET_CRYPTED) goto error; m = pkt->p_mbuf; |