ifnet: Fix decreasing the vnet interface count

It should be decreased only when the interface has been successfully
removed from the "active" list.

This prevents vnet_if_return() from potential OOB writes to the
allocated memory "pending".

Reviewed by:	kp, pouria
Fixes:		a779388f8bb3 if: Protect V_ifnet in vnet_if_return()
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D55873

1 files changed, 3 insertions, 3 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index 96da4da8c6c1..c3f31a28b40d 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -447,14 +447,14 @@ if_unlink_ifnet(struct ifnet *ifp, bool vmove)
 	CK_STAILQ_FOREACH(iter, &V_ifnet, if_link)
 		if (iter == ifp) {
 			CK_STAILQ_REMOVE(&V_ifnet, ifp, ifnet, if_link);
+#ifdef VIMAGE
+			curvnet->vnet_ifcnt--;
+#endif
 			if (!vmove)
 				ifp->if_flags |= IFF_DYING;
 			found = 1;
 			break;
 		}
-#ifdef VIMAGE
-	curvnet->vnet_ifcnt--;
-#endif
 	IFNET_WUNLOCK();
 
 	return (found);