From d94d07d58141dcff48f01c6b3e5a31de9d7a7938 Mon Sep 17 00:00:00 2001
From: Mark Johnston <markj@FreeBSD.org>
Date: Mon, 2 Oct 2023 08:08:20 -0400
Subject: [PATCH] netdump: Check the return value of ifunit_ref()

We may fail to match if the specific interface doesn't exist or was
renamed.

PR:		273715
Reported by:	grembo
MFC after:	1 week
---
 sys/netinet/netdump/netdump_client.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sys/netinet/netdump/netdump_client.c b/sys/netinet/netdump/netdump_client.c
index 35167f690ed..0f0cf4dbb79 100644
--- a/sys/netinet/netdump/netdump_client.c
+++ b/sys/netinet/netdump/netdump_client.c
@@ -451,6 +451,8 @@ netdump_configure(struct diocskerneldump_arg *conf, struct thread *td)
 		CURVNET_SET(vnet0);
 		ifp = ifunit_ref(conf->kda_iface);
 		CURVNET_RESTORE();
+		if (ifp == NULL)
+			return (ENODEV);
 		if (!DEBUGNET_SUPPORTED_NIC(ifp)) {
 			if_rele(ifp);
 			return (ENODEV);