From 8fde939b0206afc1d5846217a01a16b9bc8c7896 Mon Sep 17 00:00:00 2001 From: Julian Anastasov Date: Sat, 14 Feb 2026 16:58:50 +0200 Subject: [PATCH] ipvs: do not keep dest_dst if dev is going down There is race between the netdev notifier ip_vs_dst_event() and the code that caches dst with dev that is going down. As the FIB can be notified for the closed device after our handler finishes, it is possible valid route to be returned and cached resuling in a leaked dev reference until the dest is not removed. To prevent new dest_dst to be attached to dest just after the handler dropped the old one, add a netif_running() check to make sure the notifier handler is not currently running for device that is closing. Fixes: 7a4f0761fce3 ("IPVS: init and cleanup restructuring") Signed-off-by: Julian Anastasov Signed-off-by: Florian Westphal --- net/netfilter/ipvs/ip_vs_xmit.c | 46 ++++++++++++++++++++++++++------- 1 file changed, 36 insertions(+), 10 deletions(-) diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c index f861d116cc33..4389bfe3050d 100644 --- a/net/netfilter/ipvs/ip_vs_xmit.c +++ b/net/netfilter/ipvs/ip_vs_xmit.c @@ -294,6 +294,12 @@ static inline bool decrement_ttl(struct netns_ipvs *ipvs, return true; } +/* rt has device that is down */ +static bool rt_dev_is_down(const struct net_device *dev) +{ + return dev && !netif_running(dev); +} + /* Get route to destination or remote server */ static int __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb, @@ -309,9 +315,11 @@ __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb, if (dest) { dest_dst = __ip_vs_dst_check(dest); - if (likely(dest_dst)) + if (likely(dest_dst)) { rt = dst_rtable(dest_dst->dst_cache); - else { + if (ret_saddr) + *ret_saddr = dest_dst->dst_saddr.ip; + } else { dest_dst = ip_vs_dest_dst_alloc(); spin_lock_bh(&dest->dst_lock); if (!dest_dst) { @@ -327,14 +335,22 @@ __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb, ip_vs_dest_dst_free(dest_dst); goto err_unreach; } - __ip_vs_dst_set(dest, dest_dst, &rt->dst, 0); + /* It is forbidden to attach dest->dest_dst if + * device is going down. + */ + if (!rt_dev_is_down(dst_dev_rcu(&rt->dst))) + __ip_vs_dst_set(dest, dest_dst, &rt->dst, 0); + else + noref = 0; spin_unlock_bh(&dest->dst_lock); IP_VS_DBG(10, "new dst %pI4, src %pI4, refcnt=%d\n", &dest->addr.ip, &dest_dst->dst_saddr.ip, rcuref_read(&rt->dst.__rcuref)); + if (ret_saddr) + *ret_saddr = dest_dst->dst_saddr.ip; + if (!noref) + ip_vs_dest_dst_free(dest_dst); } - if (ret_saddr) - *ret_saddr = dest_dst->dst_saddr.ip; } else { noref = 0; @@ -471,9 +487,11 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb, if (dest) { dest_dst = __ip_vs_dst_check(dest); - if (likely(dest_dst)) + if (likely(dest_dst)) { rt = dst_rt6_info(dest_dst->dst_cache); - else { + if (ret_saddr) + *ret_saddr = dest_dst->dst_saddr.in6; + } else { u32 cookie; dest_dst = ip_vs_dest_dst_alloc(); @@ -494,14 +512,22 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb, } rt = dst_rt6_info(dst); cookie = rt6_get_cookie(rt); - __ip_vs_dst_set(dest, dest_dst, &rt->dst, cookie); + /* It is forbidden to attach dest->dest_dst if + * device is going down. + */ + if (!rt_dev_is_down(dst_dev_rcu(&rt->dst))) + __ip_vs_dst_set(dest, dest_dst, &rt->dst, cookie); + else + noref = 0; spin_unlock_bh(&dest->dst_lock); IP_VS_DBG(10, "new dst %pI6, src %pI6, refcnt=%d\n", &dest->addr.in6, &dest_dst->dst_saddr.in6, rcuref_read(&rt->dst.__rcuref)); + if (ret_saddr) + *ret_saddr = dest_dst->dst_saddr.in6; + if (!noref) + ip_vs_dest_dst_free(dest_dst); } - if (ret_saddr) - *ret_saddr = dest_dst->dst_saddr.in6; } else { noref = 0; dst = __ip_vs_route_output_v6(net, daddr, ret_saddr, do_xfrm,