From: Eric Dumazet <edumazet@google.com> mainline inclusion from mainline-v6.14-rc3 commit ed6ae1f325d3c43966ec1b62ac1459e2b8e45640 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBPC4V CVE: CVE-2025-21760 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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: David Ahern <dsahern@kernel.org> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://patch.msgid.link/20250207135841.1948589-8-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Conflicts: net/ipv6/ndisc.c [commit 696c65444120 modify param format of ndisc_send_skb(), which not merged lead to context confict] Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/ipv6/ndisc.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index 5c1d092711aa..bd3153f5a63a 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -451,16 +451,20 @@ static 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; @@ -468,6 +472,7 @@ static void ndisc_send_skb(struct sk_buff *skb, 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; } @@ -482,7 +487,6 @@ static void ndisc_send_skb(struct sk_buff *skb, ip6_nd_hdr(skb, saddr, daddr, inet6_sk(sk)->hop_limit, skb->len); - rcu_read_lock(); idev = __in6_dev_get(dst->dev); IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len); -- 2.25.1