| Message ID | 20250207135841.1948589-8-edumazet@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | ed6ae1f325d3c43966ec1b62ac1459e2b8e45640 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: second round to use dev_net_rcu() | expand |
On 2/7/25 6:58 AM, Eric Dumazet wrote: > ndisc_send_skb() can be called without RTNL or RCU held. > > Acquire rcu_read_lock() earlier, so that we can use dev_net_rcu() > and avoid a potential UAF. > > Fixes: 1762f7e88eb3 ("[NETNS][IPV6] ndisc - make socket control per namespace") > Signed-off-by: Eric Dumazet <edumazet@google.com> > --- > net/ipv6/ndisc.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > Reviewed-by: David Ahern <dsahern@kernel.org>
From: Eric Dumazet <edumazet@google.com> Date: Fri, 7 Feb 2025 13:58:39 +0000 > ndisc_send_skb() can be called without RTNL or RCU held. > > Acquire rcu_read_lock() earlier, so that we can use dev_net_rcu() > and avoid a potential UAF. > > Fixes: 1762f7e88eb3 ("[NETNS][IPV6] ndisc - make socket control per namespace") > Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index 90f8aa2d7af2ec1103220378c155b7b724efc575..8699d1a188dc4a15ac0b65229c4dd19240c9c054 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -471,16 +471,20 @@ static void ip6_nd_hdr(struct sk_buff *skb, void ndisc_send_skb(struct sk_buff *skb, const struct in6_addr *daddr, const struct in6_addr *saddr) { + struct icmp6hdr *icmp6h = icmp6_hdr(skb); struct dst_entry *dst = skb_dst(skb); - struct net *net = dev_net(skb->dev); - struct sock *sk = net->ipv6.ndisc_sk; struct inet6_dev *idev; + struct net *net; + struct sock *sk; int err; - struct icmp6hdr *icmp6h = icmp6_hdr(skb); u8 type; type = icmp6h->icmp6_type; + rcu_read_lock(); + + net = dev_net_rcu(skb->dev); + sk = net->ipv6.ndisc_sk; if (!dst) { struct flowi6 fl6; int oif = skb->dev->ifindex; @@ -488,6 +492,7 @@ void ndisc_send_skb(struct sk_buff *skb, const struct in6_addr *daddr, icmpv6_flow_init(sk, &fl6, type, saddr, daddr, oif); dst = icmp6_dst_alloc(skb->dev, &fl6); if (IS_ERR(dst)) { + rcu_read_unlock(); kfree_skb(skb); return; } @@ -502,7 +507,6 @@ void ndisc_send_skb(struct sk_buff *skb, const struct in6_addr *daddr, ip6_nd_hdr(skb, saddr, daddr, READ_ONCE(inet6_sk(sk)->hop_limit), skb->len); - rcu_read_lock(); idev = __in6_dev_get(dst->dev); IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTREQUESTS);
ndisc_send_skb() can be called without RTNL or RCU held. Acquire rcu_read_lock() earlier, so that we can use dev_net_rcu() and avoid a potential UAF. Fixes: 1762f7e88eb3 ("[NETNS][IPV6] ndisc - make socket control per namespace") Signed-off-by: Eric Dumazet <edumazet@google.com> --- net/ipv6/ndisc.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)