[PATCH 6.6.y] ipv4: start using dst_dev_rcu()
From: Robert Garcia <hidden>
Date: 2026-05-28 03:06:53
Also in:
lkml, 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 made to adapt current code. ]
Signed-off-by: Robert Garcia <redacted>
---
net/ipv4/icmp.c | 4 ++--
net/ipv4/ip_fragment.c | 6 ++++--
net/ipv4/ipmr.c | 4 ++--
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 3fcf11f83d87..29a2162398e7 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c@@ -319,16 +319,16 @@ static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, return true; /* No rate limit on loopback */ + rcu_read_lock(); if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) goto out; - rcu_read_lock(); peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, l3mdev_master_ifindex_rcu(dst->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 484edc8513e4..efc50d21d954 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c@@ -488,13 +488,15 @@ 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(skb)->dev; - 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 */ + 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;
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index af9412a507cf..948e826900fa 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c@@ -1905,7 +1905,7 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt, goto out_free; } - encap += LL_RESERVED_SPACE(dev) + rt->dst.header_len; + encap += LL_RESERVED_SPACE(dst_dev_rcu(&rt->dst)) + rt->dst.header_len; if (skb_cow(skb, encap)) { ip_rt_put(rt);
@@ -1942,7 +1942,7 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt, * result in receiving multiple packets. */ NF_HOOK(NFPROTO_IPV4, NF_INET_FORWARD, - net, NULL, skb, skb->dev, dev, + net, NULL, skb, skb->dev, dst_dev_rcu(&rt->dst), ipmr_forward_finish); return;
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index f134c59f839e..0ea017bcea47 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; + 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) {
--
2.34.1