From 27bd812c5c92af9e7acdbf100bd98166a717bb76 Mon Sep 17 00:00:00 2001
From: Kristof Provost <kp@FreeBSD.org>
Date: Thu, 2 Dec 2021 14:32:21 +0100
Subject: [PATCH] pfsync: NULL check sc before using it

In pfsync_defer() we must wait to lock sc until we've ensured it's not
NULL.

MFC after:	1 week
Sponsored by:	Rubicon Communications, LLC ("Netgate")
Differential Revision:	https://reviews.freebsd.org/D33240
---
 sys/netpfil/pf/if_pfsync.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sys/netpfil/pf/if_pfsync.c b/sys/netpfil/pf/if_pfsync.c
index 1aa5e6c0b066..166ac428fd9b 100644
--- a/sys/netpfil/pf/if_pfsync.c
+++ b/sys/netpfil/pf/if_pfsync.c
@@ -1739,9 +1739,12 @@ pfsync_defer(struct pf_kstate *st, struct mbuf *m)
 	if (m->m_flags & (M_BCAST|M_MCAST))
 		return (0);
 
+	if (sc == NULL)
+		return (0);
+
 	PFSYNC_LOCK(sc);
 
-	if (sc == NULL || !(sc->sc_ifp->if_flags & IFF_DRV_RUNNING) ||
+	if (!(sc->sc_ifp->if_flags & IFF_DRV_RUNNING) ||
 	    !(sc->sc_flags & PFSYNCF_DEFER)) {
 		PFSYNC_UNLOCK(sc);
 		return (0);