From: Eric Dumazet <edumazet@google.com> mainline inclusion from mainline-v6.14-rc3 commit 087c1faa594fa07a66933d750c0b2610aa1a2946 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBPC5R CVE: CVE-2025-21759 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- igmp6_send() can be called without RTNL or RCU being held. Extend RCU protection so that we can safely fetch the net pointer and avoid a potential UAF. Note that we no longer can use sock_alloc_send_skb() because ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep. Instead use alloc_skb() and charge the net->ipv6.igmp_sk socket under RCU protection. Fixes: b8ad0cbc58f7 ("[NETNS][IPV6] mcast - handle several network 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/20250207135841.1948589-9-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Conflicts: net/ipv6/mcast.c [commit b4a11b2033b7 separates OUTREQUESTS stastic from MIB_OUT, which not merged lead to context conflicts. commit 2e7ef287f07c convert from timer to delayed work. Because this patch was not merged, we use GFP_ATOMIC flag] Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/ipv6/mcast.c | 33 +++++++++++++++------------------ 1 file changed, 15 insertions(+), 18 deletions(-) diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index 9fb5077f8e9a..e0d5125de202 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -1974,21 +1974,21 @@ static void mld_send_cr(struct inet6_dev *idev) static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type) { - struct net *net = dev_net(dev); - struct sock *sk = net->ipv6.igmp_sk; + const struct in6_addr *snd_addr, *saddr; + int err, len, payload_len, full_len; + struct in6_addr addr_buf; struct inet6_dev *idev; struct sk_buff *skb; struct mld_msg *hdr; - const struct in6_addr *snd_addr, *saddr; - struct in6_addr addr_buf; int hlen = LL_RESERVED_SPACE(dev); int tlen = dev->needed_tailroom; - int err, len, payload_len, full_len; u8 ra[8] = { IPPROTO_ICMPV6, 0, IPV6_TLV_ROUTERALERT, 2, 0, 0, IPV6_TLV_PADN, 0 }; - struct flowi6 fl6; struct dst_entry *dst; + struct flowi6 fl6; + struct net *net; + struct sock *sk; if (type == ICMPV6_MGM_REDUCTION) snd_addr = &in6addr_linklocal_allrouters; @@ -1999,20 +1999,20 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type) payload_len = len + sizeof(ra); full_len = sizeof(struct ipv6hdr) + payload_len; - rcu_read_lock(); - IP6_UPD_PO_STATS(net, __in6_dev_get(dev), - IPSTATS_MIB_OUT, full_len); - rcu_read_unlock(); - - skb = sock_alloc_send_skb(sk, hlen + tlen + full_len, 1, &err); + skb = alloc_skb(hlen + tlen + full_len, GFP_ATOMIC); + rcu_read_lock(); + net = dev_net_rcu(dev); + idev = __in6_dev_get(dev); + IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, full_len); if (!skb) { - rcu_read_lock(); - IP6_INC_STATS(net, __in6_dev_get(dev), - IPSTATS_MIB_OUTDISCARDS); + IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); rcu_read_unlock(); return; } + sk = net->ipv6.igmp_sk; + skb_set_owner_w(skb, sk); + skb->priority = TC_PRIO_CONTROL; skb_reserve(skb, hlen); @@ -2037,9 +2037,6 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type) IPPROTO_ICMPV6, csum_partial(hdr, len, 0)); - rcu_read_lock(); - idev = __in6_dev_get(skb->dev); - icmpv6_flow_init(sk, &fl6, type, &ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr, skb->dev->ifindex); -- 2.25.1