The branch main has been updated by kevans:
URL:
https://cgit.FreeBSD.org/src/commit/?id=3705d679a6344c957cae7a1b6372a8bfb8c44f0e
commit 3705d679a6344c957cae7a1b6372a8bfb8c44f0e
Author: Kyle Evans <kev...@freebsd.org>
AuthorDate: 2024-03-15 01:19:18 +0000
Commit: Kyle Evans <kev...@freebsd.org>
CommitDate: 2024-03-15 01:19:21 +0000
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
MFC after: 1 week
Reviewed by: andrew, zlei
Differential Revision: https://reviews.freebsd.org/D44283
---
sys/dev/wg/if_wg.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/sys/dev/wg/if_wg.c b/sys/dev/wg/if_wg.c
index c7649e2b4059..42c426ac1819 100644
--- a/sys/dev/wg/if_wg.c
+++ b/sys/dev/wg/if_wg.c
@@ -1517,8 +1517,7 @@ 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);
}
@@ -1590,8 +1589,7 @@ 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);
}
@@ -1647,7 +1645,7 @@ 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;
@@ -1689,7 +1687,7 @@ 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;
