From daaaeb3051bfb9b1a030b7623778c3ec251b2b2b Mon Sep 17 00:00:00 2001
From: Kristof Provost <kp@FreeBSD.org>
Date: Tue, 5 Dec 2023 20:08:11 +0100
Subject: [PATCH] vnet: (read) lock the vnet list while iterating it

Ensure that the vnet list cannot be modified while we're running through
it.

Reviewed by:	mjg (previous version), zlei (previous version)
MFC after:	1 week
Sponsored by:	Rubicon Communications, LLC ("Netgate")
Differential Revision:	https://reviews.freebsd.org/D42927

(cherry picked from commit bd7b2f95019e9715150c34736279805de0818d09)
---
 sys/net/vnet.c         | 4 ++++
 sys/netinet/ip_reass.c | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/sys/net/vnet.c b/sys/net/vnet.c
index c4a62369834..5dec0433d31 100644
--- a/sys/net/vnet.c
+++ b/sys/net/vnet.c
@@ -503,11 +503,13 @@ vnet_register_sysinit(void *arg)
 	 * Invoke the constructor on all the existing vnets when it is
 	 * registered.
 	 */
+	VNET_LIST_RLOCK();
 	VNET_FOREACH(vnet) {
 		CURVNET_SET_QUIET(vnet);
 		vs->func(vs->arg);
 		CURVNET_RESTORE();
 	}
+	VNET_LIST_RUNLOCK();
 	VNET_SYSINIT_WUNLOCK();
 }
 
@@ -559,6 +561,7 @@ vnet_deregister_sysuninit(void *arg)
 	 * deregistered.
 	 */
 	VNET_SYSINIT_WLOCK();
+	VNET_LIST_RLOCK();
 	VNET_FOREACH(vnet) {
 		CURVNET_SET_QUIET(vnet);
 		vs->func(vs->arg);
@@ -568,6 +571,7 @@ vnet_deregister_sysuninit(void *arg)
 	/* Remove the destructor from the global list of vnet destructors. */
 	TAILQ_REMOVE(&vnet_destructors, vs, link);
 	VNET_SYSINIT_WUNLOCK();
+	VNET_LIST_RUNLOCK();
 }
 
 /*
diff --git a/sys/netinet/ip_reass.c b/sys/netinet/ip_reass.c
index 6f33c7a8a54..2876e5bfdcd 100644
--- a/sys/netinet/ip_reass.c
+++ b/sys/netinet/ip_reass.c
@@ -663,11 +663,13 @@ ipreass_drain(void)
 {
 	VNET_ITERATOR_DECL(vnet_iter);
 
+	VNET_LIST_RLOCK();
 	VNET_FOREACH(vnet_iter) {
 		CURVNET_SET(vnet_iter);
 		ipreass_drain_vnet();
 		CURVNET_RESTORE();
 	}
+	VNET_LIST_RUNLOCK();
 }