From: Eric Dumazet <edumazet@google.com> mainline inclusion from mainline-v6.14-rc5 commit 5c70eb5c593d64d93b178905da215a9fd288a4b5 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBWVSY CVE: CVE-2025-21884 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- While kernel sockets are dismantled during pernet_operations->exit(), their freeing can be delayed by any tx packets still held in qdisc or device queues, due to skb_set_owner_w() prior calls. This then trigger the following warning from ref_tracker_dir_exit() [1] To fix this, make sure that kernel sockets own a reference on net->passive. Add sk_net_refcnt_upgrade() helper, used whenever a kernel socket is converted to a refcounted one. [1] [ 136.263918][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at [ 136.263918][ T35] sk_alloc+0x2b3/0x370 [ 136.263918][ T35] inet6_create+0x6ce/0x10f0 [ 136.263918][ T35] __sock_create+0x4c0/0xa30 [ 136.263918][ T35] inet_ctl_sock_create+0xc2/0x250 [ 136.263918][ T35] igmp6_net_init+0x39/0x390 [ 136.263918][ T35] ops_init+0x31e/0x590 [ 136.263918][ T35] setup_net+0x287/0x9e0 [ 136.263918][ T35] copy_net_ns+0x33f/0x570 [ 136.263918][ T35] create_new_namespaces+0x425/0x7b0 [ 136.263918][ T35] unshare_nsproxy_namespaces+0x124/0x180 [ 136.263918][ T35] ksys_unshare+0x57d/0xa70 [ 136.263918][ T35] __x64_sys_unshare+0x38/0x40 [ 136.263918][ T35] do_syscall_64+0xf3/0x230 [ 136.263918][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 136.263918][ T35] [ 136.343488][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at [ 136.343488][ T35] sk_alloc+0x2b3/0x370 [ 136.343488][ T35] inet6_create+0x6ce/0x10f0 [ 136.343488][ T35] __sock_create+0x4c0/0xa30 [ 136.343488][ T35] inet_ctl_sock_create+0xc2/0x250 [ 136.343488][ T35] ndisc_net_init+0xa7/0x2b0 [ 136.343488][ T35] ops_init+0x31e/0x590 [ 136.343488][ T35] setup_net+0x287/0x9e0 [ 136.343488][ T35] copy_net_ns+0x33f/0x570 [ 136.343488][ T35] create_new_namespaces+0x425/0x7b0 [ 136.343488][ T35] unshare_nsproxy_namespaces+0x124/0x180 [ 136.343488][ T35] ksys_unshare+0x57d/0xa70 [ 136.343488][ T35] __x64_sys_unshare+0x38/0x40 [ 136.343488][ T35] do_syscall_64+0xf3/0x230 [ 136.343488][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: 0cafd77dcd03 ("net: add a refcount tracker for kernel sockets") Reported-by: syzbot+30a19e01a97420719891@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/67b72aeb.050a0220.14d86d.0283.GAE@google.com/... Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://patch.msgid.link/20250220131854.4048077-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- include/net/sock.h | 1 + net/core/sock.c | 27 ++++++++++++++++++++++----- net/mptcp/subflow.c | 5 +---- net/netlink/af_netlink.c | 10 ---------- net/rds/tcp.c | 8 ++------ net/smc/af_smc.c | 5 +---- net/sunrpc/svcsock.c | 5 +---- net/sunrpc/xprtsock.c | 8 ++------ 8 files changed, 30 insertions(+), 39 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index 330afe640f02..81050e48698e 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1886,6 +1886,7 @@ static inline bool sock_allow_reclassification(const struct sock *csk) struct sock *sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot, int kern); void sk_free(struct sock *sk); +void sk_net_refcnt_upgrade(struct sock *sk); void sk_destruct(struct sock *sk); struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority); void sk_free_unlock_clone(struct sock *sk); diff --git a/net/core/sock.c b/net/core/sock.c index 93ee2bba32f6..1e27275bb24f 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2159,6 +2159,7 @@ struct sock *sk_alloc(struct net *net, int family, gfp_t priority, get_net_track(net, &sk->ns_tracker, priority); sock_inuse_add(net, 1); } else { + net_passive_inc(net); __netns_tracker_alloc(net, &sk->ns_tracker, false, priority); } @@ -2183,6 +2184,7 @@ EXPORT_SYMBOL(sk_alloc); static void __sk_destruct(struct rcu_head *head) { struct sock *sk = container_of(head, struct sock, sk_rcu); + struct net *net = sock_net(sk); struct sk_filter *filter; if (sk->sk_destruct) @@ -2214,14 +2216,28 @@ static void __sk_destruct(struct rcu_head *head) put_cred(sk->sk_peer_cred); put_pid(sk->sk_peer_pid); - if (likely(sk->sk_net_refcnt)) - put_net_track(sock_net(sk), &sk->ns_tracker); - else - __netns_tracker_free(sock_net(sk), &sk->ns_tracker, false); - + if (likely(sk->sk_net_refcnt)) { + put_net_track(net, &sk->ns_tracker); + } else { + __netns_tracker_free(net, &sk->ns_tracker, false); + net_passive_dec(net); + } sk_prot_free(sk->sk_prot_creator, sk); } +void sk_net_refcnt_upgrade(struct sock *sk) +{ + struct net *net = sock_net(sk); + + WARN_ON_ONCE(sk->sk_net_refcnt); + __netns_tracker_free(net, &sk->ns_tracker, false); + net_passive_dec(net); + sk->sk_net_refcnt = 1; + get_net_track(net, &sk->ns_tracker, GFP_KERNEL); + sock_inuse_add(net, 1); +} +EXPORT_SYMBOL_GPL(sk_net_refcnt_upgrade); + void sk_destruct(struct sock *sk) { bool use_call_rcu = sock_flag(sk, SOCK_RCU_FREE); @@ -2313,6 +2329,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority) * is not properly dismantling its kernel sockets at netns * destroy time. */ + net_passive_inc(sock_net(newsk)); __netns_tracker_alloc(sock_net(newsk), &newsk->ns_tracker, false, priority); } diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 11002495246a..87d289adaa3f 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1723,10 +1723,7 @@ int mptcp_subflow_create_socket(struct sock *sk, unsigned short family, * needs it. * Update ns_tracker to current stack trace and refcounted tracker. */ - __netns_tracker_free(net, &sf->sk->ns_tracker, false); - sf->sk->sk_net_refcnt = 1; - get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL); - sock_inuse_add(net, 1); + sk_net_refcnt_upgrade(sf->sk); err = tcp_set_ulp(sf->sk, "mptcp"); if (err) goto err_free; diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 4aa2cbe9d6fa..cdb66eb0c3fa 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -799,16 +799,6 @@ static int netlink_release(struct socket *sock) sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1); - /* Because struct net might disappear soon, do not keep a pointer. */ - if (!sk->sk_net_refcnt && sock_net(sk) != &init_net) { - __netns_tracker_free(sock_net(sk), &sk->ns_tracker, false); - /* Because of deferred_put_nlk_sk and use of work queue, - * it is possible netns will be freed before this socket. - */ - sock_net_set(sk, &init_net); - __netns_tracker_alloc(&init_net, &sk->ns_tracker, - false, GFP_KERNEL); - } call_rcu(&nlk->rcu, deferred_put_nlk_sk); return 0; } diff --git a/net/rds/tcp.c b/net/rds/tcp.c index fb6eaea36014..e5d90e4beb35 100644 --- a/net/rds/tcp.c +++ b/net/rds/tcp.c @@ -505,12 +505,8 @@ bool rds_tcp_tune(struct socket *sock) release_sock(sk); return false; } - /* Update ns_tracker to current stack trace and refcounted tracker */ - __netns_tracker_free(net, &sk->ns_tracker, false); - - sk->sk_net_refcnt = 1; - netns_tracker_alloc(net, &sk->ns_tracker, GFP_KERNEL); - sock_inuse_add(net, 1); + sk_net_refcnt_upgrade(sk); + put_net(net); } rtn = net_generic(net, rds_tcp_netid); if (rtn->sndbuf_size > 0) { diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index df0654d7f352..99a815bc42f8 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -3344,10 +3344,7 @@ int smc_create_clcsk(struct net *net, struct sock *sk, int family) * which need net ref. */ sk = smc->clcsock->sk; - __netns_tracker_free(net, &sk->ns_tracker, false); - sk->sk_net_refcnt = 1; - get_net_track(net, &sk->ns_tracker, GFP_KERNEL); - sock_inuse_add(net, 1); + sk_net_refcnt_upgrade(sk); return 0; } diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c index 8d760f8fc4b5..f591ead0d961 100644 --- a/net/sunrpc/svcsock.c +++ b/net/sunrpc/svcsock.c @@ -1552,10 +1552,7 @@ static struct svc_xprt *svc_create_socket(struct svc_serv *serv, newlen = error; if (protocol == IPPROTO_TCP) { - __netns_tracker_free(net, &sock->sk->ns_tracker, false); - sock->sk->sk_net_refcnt = 1; - get_net_track(net, &sock->sk->ns_tracker, GFP_KERNEL); - sock_inuse_add(net, 1); + sk_net_refcnt_upgrade(sock->sk); if ((error = kernel_listen(sock, 64)) < 0) goto bummer; } diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 29df05879c8e..4e6313fac366 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -1921,12 +1921,8 @@ static struct socket *xs_create_sock(struct rpc_xprt *xprt, goto out; } - if (protocol == IPPROTO_TCP) { - __netns_tracker_free(xprt->xprt_net, &sock->sk->ns_tracker, false); - sock->sk->sk_net_refcnt = 1; - get_net_track(xprt->xprt_net, &sock->sk->ns_tracker, GFP_KERNEL); - sock_inuse_add(xprt->xprt_net, 1); - } + if (protocol == IPPROTO_TCP) + sk_net_refcnt_upgrade(sock->sk); filp = sock_alloc_file(sock, O_NONBLOCK, NULL); if (IS_ERR(filp)) -- 2.25.1