[PATCH 6.6.y 4/4] ipv4: start using dst_dev_rcu()
From: Miguel Gazquez (Schneider Electric) <hidden>
Date: 2026-08-31 16:06:44
Also in:
lkml, netfilter-devel, stable
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
From: Eric Dumazet <edumazet@google.com>
[ Upstream commit 6ad8de3cefdb6ffa6708b21c567df0dbf82c43a8 ]
Change icmpv4_xrlim_allow(), ip_defrag() to prevent possible UAF.
Change ipmr_prepare_xmit(), ipmr_queue_fwd_xmit(), ip_mr_output(),
ipv4_neigh_lookup() to use lockdep enabled dst_dev_rcu().
Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20250828195823.3958522-9-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ minor modifications to fix conflict ]
Signed-off-by: Miguel Gazquez (Schneider Electric) <redacted>
---
net/ipv4/icmp.c | 6 +++---
net/ipv4/ip_fragment.c | 6 ++++--
net/ipv4/ipmr.c | 2 +-
net/ipv4/route.c | 4 ++--
4 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index f0c8c3366740..5c38af80bc14 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c@@ -320,17 +320,17 @@ static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, return true; /* No rate limit on loopback */ - dev = dst_dev(dst); + rcu_read_lock(); + dev = dst_dev_rcu(dst); if (dev && (dev->flags & IFF_LOOPBACK)) goto out; - rcu_read_lock(); peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, l3mdev_master_ifindex_rcu(dev)); rc = inet_peer_xrlim_allow(peer, READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); - rcu_read_unlock(); out: + rcu_read_unlock(); if (!rc) __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); else
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 46b84d029205..e79ebe911548 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c@@ -470,14 +470,16 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb, /* Process an incoming IP datagram fragment. */ int ip_defrag(struct net *net, struct sk_buff *skb, u32 user) { - struct net_device *dev = skb->dev ? : skb_dst_dev(skb); - int vif = l3mdev_master_ifindex_rcu(dev); + struct net_device *dev; struct ipq *qp; + int vif; __IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS); /* Lookup (or create) queue header */ rcu_read_lock(); + dev = skb->dev ? : skb_dst_dev_rcu(skb); + vif = l3mdev_master_ifindex_rcu(dev); qp = ip_find(net, ip_hdr(skb), user, vif); if (qp) { int ret, refs = 0;
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index af9412a507cf..f39cd565569a 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c@@ -1893,7 +1893,7 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt, goto out_free; } - dev = rt->dst.dev; + dev = dst_dev_rcu(&rt->dst); if (skb->len+encap > dst_mtu(&rt->dst) && (ntohs(iph->frag_off) & IP_DF)) { /* Do not fragment multicasts. Alas, IPv4 does not
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index ce3397583b8f..b175a8292eb3 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c@@ -416,11 +416,11 @@ static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst, const void *daddr) { const struct rtable *rt = container_of(dst, struct rtable, dst); - struct net_device *dev = dst_dev(dst); + struct net_device *dev; struct neighbour *n; rcu_read_lock(); - + dev = dst_dev_rcu(dst); if (likely(rt->rt_gw_family == AF_INET)) { n = ip_neigh_gw4(dev, rt->rt_gw4); } else if (rt->rt_gw_family == AF_INET6) {
--
2.55.0