From f214fc402967e1bc94ad7f39faa03db5813d6849 Mon Sep 17 00:00:00 2001 From: Parthasarathy Bhuvaragan Date: Tue, 1 Mar 2016 11:07:09 +0100 Subject: tipc: Revert "tipc: use existing sk_write_queue for outgoing packet chain" reverts commit 94153e36e709e ("tipc: use existing sk_write_queue for outgoing packet chain") In Commit 94153e36e709e, we assume that we fill & empty the socket's sk_write_queue within the same lock_sock() session. This is not true if the link is congested. During congestion, the socket lock is released while we wait for the congestion to cease. This implementation causes a nullptr exception, if the user space program has several threads accessing the same socket descriptor. Consider two threads of the same program performing the following: Thread1 Thread2 -------------------- ---------------------- Enter tipc_sendmsg() Enter tipc_sendmsg() lock_sock() lock_sock() Enter tipc_link_xmit(), ret=ELINKCONG spin on socket lock.. sk_wait_event() : release_sock() grab socket lock : Enter tipc_link_xmit(), ret=0 : release_sock() Wakeup after congestion lock_sock() skb = skb_peek(pktchain); !! TIPC_SKB_CB(skb)->wakeup_pending = tsk->link_cong; In this case, the second thread transmits the buffers belonging to both thread1 and thread2 successfully. When the first thread wakeup after the congestion it assumes that the pktchain is intact and operates on the skb's in it, which leads to the following exception: [2102.439969] BUG: unable to handle kernel NULL pointer dereference at 00000000000000d0 [2102.440074] IP: [] __tipc_link_xmit+0x2b0/0x4d0 [tipc] [2102.440074] PGD 3fa3f067 PUD 3fa6b067 PMD 0 [2102.440074] Oops: 0000 [#1] SMP [2102.440074] CPU: 2 PID: 244 Comm: sender Not tainted 3.12.28 #1 [2102.440074] RIP: 0010:[] [] __tipc_link_xmit+0x2b0/0x4d0 [tipc] [...] [2102.440074] Call Trace: [2102.440074] [] ? schedule+0x29/0x70 [2102.440074] [] ? tipc_node_unlock+0x46/0x170 [tipc] [2102.440074] [] tipc_link_xmit+0x51/0xf0 [tipc] [2102.440074] [] tipc_send_stream+0x11e/0x4f0 [tipc] [2102.440074] [] ? __wake_up_sync+0x20/0x20 [2102.440074] [] tipc_send_packet+0x1c/0x20 [tipc] [2102.440074] [] sock_sendmsg+0xa8/0xd0 [2102.440074] [] ? release_sock+0x145/0x170 [2102.440074] [] ___sys_sendmsg+0x3d8/0x3e0 [2102.440074] [] ? _raw_spin_unlock+0xe/0x10 [2102.440074] [] ? handle_mm_fault+0x6ca/0x9d0 [2102.440074] [] ? set_next_entity+0x85/0xa0 [2102.440074] [] ? _raw_spin_unlock_irq+0xe/0x20 [2102.440074] [] ? finish_task_switch+0x5c/0xc0 [2102.440074] [] ? __schedule+0x34c/0x950 [2102.440074] [] __sys_sendmsg+0x42/0x80 [2102.440074] [] SyS_sendmsg+0x12/0x20 [2102.440074] [] system_call_fastpath+0x16/0x1b In this commit, we maintain the skb list always in the stack. Signed-off-by: Parthasarathy Bhuvaragan Acked-by: Ying Xue Acked-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/socket.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) (limited to 'net/tipc') diff --git a/net/tipc/socket.c b/net/tipc/socket.c index 69c2905..4d420bb 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -673,7 +673,7 @@ static int tipc_sendmcast(struct socket *sock, struct tipc_name_seq *seq, struct tipc_sock *tsk = tipc_sk(sk); struct net *net = sock_net(sk); struct tipc_msg *mhdr = &tsk->phdr; - struct sk_buff_head *pktchain = &sk->sk_write_queue; + struct sk_buff_head pktchain; struct iov_iter save = msg->msg_iter; uint mtu; int rc; @@ -687,14 +687,16 @@ static int tipc_sendmcast(struct socket *sock, struct tipc_name_seq *seq, msg_set_nameupper(mhdr, seq->upper); msg_set_hdr_sz(mhdr, MCAST_H_SIZE); + skb_queue_head_init(&pktchain); + new_mtu: mtu = tipc_bcast_get_mtu(net); - rc = tipc_msg_build(mhdr, msg, 0, dsz, mtu, pktchain); + rc = tipc_msg_build(mhdr, msg, 0, dsz, mtu, &pktchain); if (unlikely(rc < 0)) return rc; do { - rc = tipc_bcast_xmit(net, pktchain); + rc = tipc_bcast_xmit(net, &pktchain); if (likely(!rc)) return dsz; @@ -704,7 +706,7 @@ new_mtu: if (!rc) continue; } - __skb_queue_purge(pktchain); + __skb_queue_purge(&pktchain); if (rc == -EMSGSIZE) { msg->msg_iter = save; goto new_mtu; @@ -863,7 +865,7 @@ static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dsz) struct net *net = sock_net(sk); struct tipc_msg *mhdr = &tsk->phdr; u32 dnode, dport; - struct sk_buff_head *pktchain = &sk->sk_write_queue; + struct sk_buff_head pktchain; struct sk_buff *skb; struct tipc_name_seq *seq; struct iov_iter save; @@ -924,17 +926,18 @@ static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dsz) msg_set_hdr_sz(mhdr, BASIC_H_SIZE); } + skb_queue_head_init(&pktchain); save = m->msg_iter; new_mtu: mtu = tipc_node_get_mtu(net, dnode, tsk->portid); - rc = tipc_msg_build(mhdr, m, 0, dsz, mtu, pktchain); + rc = tipc_msg_build(mhdr, m, 0, dsz, mtu, &pktchain); if (rc < 0) return rc; do { - skb = skb_peek(pktchain); + skb = skb_peek(&pktchain); TIPC_SKB_CB(skb)->wakeup_pending = tsk->link_cong; - rc = tipc_node_xmit(net, pktchain, dnode, tsk->portid); + rc = tipc_node_xmit(net, &pktchain, dnode, tsk->portid); if (likely(!rc)) { if (sock->state != SS_READY) sock->state = SS_CONNECTING; @@ -946,7 +949,7 @@ new_mtu: if (!rc) continue; } - __skb_queue_purge(pktchain); + __skb_queue_purge(&pktchain); if (rc == -EMSGSIZE) { m->msg_iter = save; goto new_mtu; @@ -1016,7 +1019,7 @@ static int __tipc_send_stream(struct socket *sock, struct msghdr *m, size_t dsz) struct net *net = sock_net(sk); struct tipc_sock *tsk = tipc_sk(sk); struct tipc_msg *mhdr = &tsk->phdr; - struct sk_buff_head *pktchain = &sk->sk_write_queue; + struct sk_buff_head pktchain; DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name); u32 portid = tsk->portid; int rc = -EINVAL; @@ -1044,17 +1047,19 @@ static int __tipc_send_stream(struct socket *sock, struct msghdr *m, size_t dsz) timeo = sock_sndtimeo(sk, m->msg_flags & MSG_DONTWAIT); dnode = tsk_peer_node(tsk); + skb_queue_head_init(&pktchain); next: save = m->msg_iter; mtu = tsk->max_pkt; send = min_t(uint, dsz - sent, TIPC_MAX_USER_MSG_SIZE); - rc = tipc_msg_build(mhdr, m, sent, send, mtu, pktchain); + rc = tipc_msg_build(mhdr, m, sent, send, mtu, &pktchain); if (unlikely(rc < 0)) return rc; + do { if (likely(!tsk_conn_cong(tsk))) { - rc = tipc_node_xmit(net, pktchain, dnode, portid); + rc = tipc_node_xmit(net, &pktchain, dnode, portid); if (likely(!rc)) { tsk->sent_unacked++; sent += send; @@ -1063,7 +1068,7 @@ next: goto next; } if (rc == -EMSGSIZE) { - __skb_queue_purge(pktchain); + __skb_queue_purge(&pktchain); tsk->max_pkt = tipc_node_get_mtu(net, dnode, portid); m->msg_iter = save; @@ -1077,7 +1082,7 @@ next: rc = tipc_wait_for_sndpkt(sock, &timeo); } while (!rc); - __skb_queue_purge(pktchain); + __skb_queue_purge(&pktchain); return sent ? sent : rc; } -- cgit v1.1 From 4de13d7ed6ffdcbb34317acaa9236f121176f5f8 Mon Sep 17 00:00:00 2001 From: Parthasarathy Bhuvaragan Date: Thu, 3 Mar 2016 17:54:54 +0100 Subject: tipc: fix nullptr crash during subscription cancel commit 4d5cfcba2f6e ('tipc: fix connection abort during subscription cancel'), removes the check for a valid subscription before calling tipc_nametbl_subscribe(). This will lead to a nullptr exception when we process a subscription cancel request. For a cancel request, a null subscription is passed to tipc_nametbl_subscribe() resulting in exception. In this commit, we call tipc_nametbl_subscribe() only for a valid subscription. Fixes: 4d5cfcba2f6e ('tipc: fix connection abort during subscription cancel') Reported-by: Anders Widell Signed-off-by: Parthasarathy Bhuvaragan Acked-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/subscr.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/tipc') diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c index 69ee2ee..f9ff73a 100644 --- a/net/tipc/subscr.c +++ b/net/tipc/subscr.c @@ -296,7 +296,8 @@ static void tipc_subscrb_rcv_cb(struct net *net, int conid, if (tipc_subscrp_create(net, (struct tipc_subscr *)buf, subscrb, &sub)) return tipc_conn_terminate(tn->topsrv, subscrb->conid); - tipc_nametbl_subscribe(sub); + if (sub) + tipc_nametbl_subscribe(sub); } /* Handle one request to establish a new subscriber */ -- cgit v1.1