Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932155AbcDRDGx (ORCPT ); Sun, 17 Apr 2016 23:06:53 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36489 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754411AbcDRCgh (ORCPT ); Sun, 17 Apr 2016 22:36:37 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Parthasarathy Bhuvaragan , Ying Xue , Jon Maloy , "David S. Miller" Subject: [PATCH 4.4 034/137] tipc: Revert "tipc: use existing sk_write_queue for outgoing packet chain" Date: Mon, 18 Apr 2016 11:28:16 +0900 Message-Id: <20160418022509.526286234@linuxfoundation.org> X-Mailer: git-send-email 2.8.0 In-Reply-To: <20160418022507.236379264@linuxfoundation.org> References: <20160418022507.236379264@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7512 Lines: 206 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Parthasarathy Bhuvaragan [ Upstream commit f214fc402967e1bc94ad7f39faa03db5813d6849 ] 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 Signed-off-by: Greg Kroah-Hartman --- net/tipc/socket.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -673,7 +673,7 @@ static int tipc_sendmcast(struct socket 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 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 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 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 soc 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 soc 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; }