Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock() is done too late. After tcp_v4_syn_recv_sock(), the child socket is already visible from TCP ehash table and other cpus might use it. Since newinet->pinet6 is still pointing to the listener ipv6_pinfo bad things can happen as syzbot found. Move the problematic code in tcp_v6_mapped_child_init() and call this new helper from tcp_v4_syn_recv_sock() before the ehash insertion. This allows the removal of one tcp_sync_mss(), since tcp_v4_syn_recv_sock() will call it with the correct context. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+937b5bbb6a815b3e5d0b@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/69949275.050a0220.2eeac1.0145.GAE@google.com/ Signed-off-by: Eric Dumazet --- include/net/inet_connection_sock.h | 4 +- include/net/tcp.h | 4 +- net/ipv4/syncookies.c | 2 +- net/ipv4/tcp_fastopen.c | 2 +- net/ipv4/tcp_ipv4.c | 8 ++- net/ipv4/tcp_minisocks.c | 2 +- net/ipv6/tcp_ipv6.c | 98 +++++++++++++----------------- net/mptcp/subflow.c | 6 +- net/smc/af_smc.c | 6 +- 9 files changed, 66 insertions(+), 66 deletions(-) diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h index ecb362025c4e5183ec78aef4b45c249da87c19ea..5cb3056d6ddc7cb9489131f503b32f3dac211bec 100644 --- a/include/net/inet_connection_sock.h +++ b/include/net/inet_connection_sock.h @@ -42,7 +42,9 @@ struct inet_connection_sock_af_ops { struct request_sock *req, struct dst_entry *dst, struct request_sock *req_unhash, - bool *own_req); + bool *own_req, + void (*opt_child_init)(struct sock *newsk, + const struct sock *sk)); u16 net_header_len; int (*setsockopt)(struct sock *sk, int level, int optname, sockptr_t optval, unsigned int optlen); diff --git a/include/net/tcp.h b/include/net/tcp.h index 40e72b9cb85f08714d3f458c0bd1402a5fb1eb4e..eb8bf63fdafc3243469f293fd06aef0ce086c5a4 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -544,7 +544,9 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, struct request_sock *req, struct dst_entry *dst, struct request_sock *req_unhash, - bool *own_req); + bool *own_req, + void (*opt_child_init)(struct sock *newsk, + const struct sock *sk)); int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); int tcp_v4_connect(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len); int tcp_connect(struct sock *sk); diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c index 569befcf021ba5598e57ee3256843c141aeb412b..061751aabc8e16c5d536a19f7b920d1bca2b0f4f 100644 --- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -203,7 +203,7 @@ struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, bool own_req; child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst, - NULL, &own_req); + NULL, &own_req, NULL); if (child) { refcount_set(&req->rsk_refcnt, 1); sock_rps_save_rxhash(child, skb); diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c index b30090cff3cf7d925dc46694860abd3ca5516d70..df803f088f454cf157e0efbba8e2ff3f6d205530 100644 --- a/net/ipv4/tcp_fastopen.c +++ b/net/ipv4/tcp_fastopen.c @@ -333,7 +333,7 @@ static struct sock *tcp_fastopen_create_child(struct sock *sk, bool own_req; child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL, - NULL, &own_req); + NULL, &own_req, NULL); if (!child) return NULL; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 6264fc0b2be53854598d7c37ce1c7928d2e0b507..2980c175d326b6c6ebd4acba0c4333f481617579 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1705,7 +1705,9 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, struct request_sock *req, struct dst_entry *dst, struct request_sock *req_unhash, - bool *own_req) + bool *own_req, + void (*opt_child_init)(struct sock *newsk, + const struct sock *sk)) { struct inet_request_sock *ireq; bool found_dup_sk = false; @@ -1757,6 +1759,10 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, } sk_setup_caps(newsk, dst); +#if IS_ENABLED(CONFIG_IPV6) + if (opt_child_init) + opt_child_init(newsk, sk); +#endif tcp_ca_openreq_child(newsk, dst); tcp_sync_mss(newsk, dst4_mtu(dst)); diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index ec128865f5c029c971eb00cb9ee058b742efafd1..d9c5a43bd2818c17d79d8433ac5dd2bdd199b812 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -925,7 +925,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, * socket is created, wait for troubles. */ child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL, - req, &own_req); + req, &own_req, NULL); if (!child) goto listen_overflow; diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index d10487b4e5bff87d4ff2a7b912a826964101a163..e46a0efae01235ae7430ed268b92cb47309b8d28 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1312,11 +1312,48 @@ static void tcp_v6_restore_cb(struct sk_buff *skb) sizeof(struct inet6_skb_parm)); } +/* Called from tcp_v4_syn_recv_sock() for v6_mapped children. */ +static void tcp_v6_mapped_child_init(struct sock *newsk, const struct sock *sk) +{ + struct inet_sock *newinet = inet_sk(newsk); + struct ipv6_pinfo *newnp; + + newinet->pinet6 = newnp = tcp_inet6_sk(newsk); + newinet->ipv6_fl_list = NULL; + + memcpy(newnp, tcp_inet6_sk(sk), sizeof(struct ipv6_pinfo)); + + newnp->saddr = newsk->sk_v6_rcv_saddr; + + inet_csk(newsk)->icsk_af_ops = &ipv6_mapped; + if (sk_is_mptcp(newsk)) + mptcpv6_handle_mapped(newsk, true); + newsk->sk_backlog_rcv = tcp_v4_do_rcv; +#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO) + tcp_sk(newsk)->af_specific = &tcp_sock_ipv6_mapped_specific; +#endif + + newnp->ipv6_mc_list = NULL; + newnp->ipv6_ac_list = NULL; + newnp->pktoptions = NULL; + newnp->opt = NULL; + + /* tcp_v4_syn_recv_sock() has initialized newinet->mc_{index,ttl} */ + newnp->mcast_oif = newinet->mc_index; + newnp->mcast_hops = newinet->mc_ttl; + + newnp->rcv_flowinfo = 0; + if (inet6_test_bit(REPFLOW, sk)) + newnp->flow_label = 0; +} + static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, struct request_sock *req, struct dst_entry *dst, struct request_sock *req_unhash, - bool *own_req) + bool *own_req, + void (*opt_child_init)(struct sock *newsk, + const struct sock *sk)) { const struct ipv6_pinfo *np = tcp_inet6_sk(sk); struct inet_request_sock *ireq; @@ -1332,61 +1369,10 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff * #endif struct flowi6 fl6; - if (skb->protocol == htons(ETH_P_IP)) { - /* - * v6 mapped - */ - - newsk = tcp_v4_syn_recv_sock(sk, skb, req, dst, - req_unhash, own_req); - - if (!newsk) - return NULL; - - newinet = inet_sk(newsk); - newinet->pinet6 = tcp_inet6_sk(newsk); - newinet->ipv6_fl_list = NULL; - - newnp = tcp_inet6_sk(newsk); - newtp = tcp_sk(newsk); - - memcpy(newnp, np, sizeof(struct ipv6_pinfo)); - - newnp->saddr = newsk->sk_v6_rcv_saddr; - - inet_csk(newsk)->icsk_af_ops = &ipv6_mapped; - if (sk_is_mptcp(newsk)) - mptcpv6_handle_mapped(newsk, true); - newsk->sk_backlog_rcv = tcp_v4_do_rcv; -#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO) - newtp->af_specific = &tcp_sock_ipv6_mapped_specific; -#endif - - newnp->ipv6_mc_list = NULL; - newnp->ipv6_ac_list = NULL; - newnp->pktoptions = NULL; - newnp->opt = NULL; - newnp->mcast_oif = inet_iif(skb); - newnp->mcast_hops = ip_hdr(skb)->ttl; - newnp->rcv_flowinfo = 0; - if (inet6_test_bit(REPFLOW, sk)) - newnp->flow_label = 0; - - /* - * No need to charge this sock to the relevant IPv6 refcnt debug socks count - * here, tcp_create_openreq_child now does this for us, see the comment in - * that function for the gory details. -acme - */ - - /* It is tricky place. Until this moment IPv4 tcp - worked with IPv6 icsk.icsk_af_ops. - Sync it now. - */ - tcp_sync_mss(newsk, inet_csk(newsk)->icsk_pmtu_cookie); - - return newsk; - } - + if (skb->protocol == htons(ETH_P_IP)) + return tcp_v4_syn_recv_sock(sk, skb, req, dst, + req_unhash, own_req, + tcp_v6_mapped_child_init); ireq = inet_rsk(req); if (sk_acceptq_is_full(sk)) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index f66129f1e649248e00215d254c925f66c3fffa6a..8b25dd86ffeb668b98fd41026fb084dab7dc23b8 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -808,7 +808,9 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, struct request_sock *req, struct dst_entry *dst, struct request_sock *req_unhash, - bool *own_req) + bool *own_req, + void (*opt_child_init)(struct sock *newsk, + const struct sock *sk)) { struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk); struct mptcp_subflow_request_sock *subflow_req; @@ -855,7 +857,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, create_child: child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst, - req_unhash, own_req); + req_unhash, own_req, opt_child_init); if (child && *own_req) { struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child); diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index d8201eb3ac5f3d87a15f385862c4ae82ae3a24ff..18c56b0d7ad531e575266ad7f38187973422151f 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -124,7 +124,9 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk, struct request_sock *req, struct dst_entry *dst, struct request_sock *req_unhash, - bool *own_req) + bool *own_req, + void (*opt_child_init)(struct sock *newsk, + const struct sock *sk)) { struct smc_sock *smc; struct sock *child; @@ -142,7 +144,7 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk, /* passthrough to original syn recv sock fct */ child = smc->ori_af_ops->syn_recv_sock(sk, skb, req, dst, req_unhash, - own_req); + own_req, opt_child_init); /* child must not inherit smc or its ops */ if (child) { rcu_assign_sk_user_data(child, NULL); -- 2.53.0.310.g728cabbaf7-goog