[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20250828195823.3958522-4-edumazet@google.com>
Date: Thu, 28 Aug 2025 19:58:18 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, Neal Cardwell <ncardwell@...gle.com>
Cc: Simon Horman <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...gle.com>,
David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 3/8] ipv6: use RCU in ip6_xmit()
Use RCU in ip6_xmit() in order to use dst_dev_rcu() to prevent
possible UAF.
Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/ipv6/ip6_output.c | 35 +++++++++++++++++++++--------------
1 file changed, 21 insertions(+), 14 deletions(-)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 1e1410237b6ef0eca7a0aac13c4d7c56a77e0252..e234640433d6b30d3c13d8367dbe7270ddb2c9d7 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -268,35 +268,36 @@ bool ip6_autoflowlabel(struct net *net, const struct sock *sk)
int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
__u32 mark, struct ipv6_txoptions *opt, int tclass, u32 priority)
{
- struct net *net = sock_net(sk);
const struct ipv6_pinfo *np = inet6_sk(sk);
struct in6_addr *first_hop = &fl6->daddr;
struct dst_entry *dst = skb_dst(skb);
- struct net_device *dev = dst_dev(dst);
struct inet6_dev *idev = ip6_dst_idev(dst);
struct hop_jumbo_hdr *hop_jumbo;
int hoplen = sizeof(*hop_jumbo);
+ struct net *net = sock_net(sk);
unsigned int head_room;
+ struct net_device *dev;
struct ipv6hdr *hdr;
u8 proto = fl6->flowi6_proto;
int seg_len = skb->len;
- int hlimit = -1;
+ int ret, hlimit = -1;
u32 mtu;
+ rcu_read_lock();
+
+ dev = dst_dev_rcu(dst);
head_room = sizeof(struct ipv6hdr) + hoplen + LL_RESERVED_SPACE(dev);
if (opt)
head_room += opt->opt_nflen + opt->opt_flen;
if (unlikely(head_room > skb_headroom(skb))) {
- /* Make sure idev stays alive */
- rcu_read_lock();
+ /* idev stays alive while we hold rcu_read_lock(). */
skb = skb_expand_head(skb, head_room);
if (!skb) {
IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
- rcu_read_unlock();
- return -ENOBUFS;
+ ret = -ENOBUFS;
+ goto unlock;
}
- rcu_read_unlock();
}
if (opt) {
@@ -358,17 +359,21 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
* skb to its handler for processing
*/
skb = l3mdev_ip6_out((struct sock *)sk, skb);
- if (unlikely(!skb))
- return 0;
+ if (unlikely(!skb)) {
+ ret = 0;
+ goto unlock;
+ }
/* hooks should never assume socket lock is held.
* we promote our socket to non const
*/
- return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
- net, (struct sock *)sk, skb, NULL, dev,
- dst_output);
+ ret = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
+ net, (struct sock *)sk, skb, NULL, dev,
+ dst_output);
+ goto unlock;
}
+ ret = -EMSGSIZE;
skb->dev = dev;
/* ipv6_local_error() does not require socket lock,
* we promote our socket to non const
@@ -377,7 +382,9 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
IP6_INC_STATS(net, idev, IPSTATS_MIB_FRAGFAILS);
kfree_skb(skb);
- return -EMSGSIZE;
+unlock:
+ rcu_read_unlock();
+ return ret;
}
EXPORT_SYMBOL(ip6_xmit);
--
2.51.0.318.gd7df087d1a-goog
Powered by blists - more mailing lists