From 8072699aa9e67d1727692cfb3c347263bb627fb9 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Thu, 18 Jan 2024 16:58:59 -0800 Subject: [PATCH] net: fix removing a namespace with conflicting altnames MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit d09486a04f5da0a812c26217213b89a3b1acf836 ] Mark reports a BUG() when a net namespace is removed. kernel BUG at net/core/dev.c:11520! Physical interfaces moved outside of init_net get "refunded" to init_net when that namespace disappears. The main interface name may get overwritten in the process if it would have conflicted. We need to also discard all conflicting altnames. Recent fixes addressed ensuring that altnames get moved with the main interface, which surfaced this problem. Reported-by: Марк Коренберг Link: https://lore.kernel.org/all/CAEmTpZFZ4Sv3KwqFOY2WKDHeZYdi0O7N5H1nTvcGp=SAEavtDg@mail.gmail.com/ Fixes: 7663d522099e ("net: check for altname conflicts when changing netdev's netns") Signed-off-by: Jakub Kicinski Reviewed-by: Eric Dumazet Reviewed-by: Jiri Pirko Reviewed-by: Xin Long Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/core/dev.c | 9 +++++++++ net/core/dev.h | 3 +++ 2 files changed, 12 insertions(+) diff --git a/net/core/dev.c b/net/core/dev.c index ad20bebe153f..add22ca0dff9 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -11509,6 +11509,7 @@ static struct pernet_operations __net_initdata netdev_net_ops = { static void __net_exit default_device_exit_net(struct net *net) { + struct netdev_name_node *name_node, *tmp; struct net_device *dev, *aux; /* * Push all migratable network devices back to the @@ -11531,6 +11532,14 @@ static void __net_exit default_device_exit_net(struct net *net) snprintf(fb_name, IFNAMSIZ, "dev%d", dev->ifindex); if (netdev_name_in_use(&init_net, fb_name)) snprintf(fb_name, IFNAMSIZ, "dev%%d"); + + netdev_for_each_altname_safe(dev, name_node, tmp) + if (netdev_name_in_use(&init_net, name_node->name)) { + netdev_name_node_del(name_node); + synchronize_rcu(); + __netdev_name_node_alt_destroy(name_node); + } + err = dev_change_net_namespace(dev, &init_net, fb_name); if (err) { pr_emerg("%s: failed to move %s to init_net: %d\n", diff --git a/net/core/dev.h b/net/core/dev.h index 5aa45f0fd4ae..3f5eb92396b6 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -64,6 +64,9 @@ int dev_change_name(struct net_device *dev, const char *newname); #define netdev_for_each_altname(dev, namenode) \ list_for_each_entry((namenode), &(dev)->name_node->list, list) +#define netdev_for_each_altname_safe(dev, namenode, next) \ + list_for_each_entry_safe((namenode), (next), &(dev)->name_node->list, \ + list) int netdev_name_node_alt_create(struct net_device *dev, const char *name); int netdev_name_node_alt_destroy(struct net_device *dev, const char *name);