kernel/linux.git/net/ipv4, branch linux-4.13.y

tcp: fix tcp_fastretrans_alert warning

2017-11-24T07:35:56+00:00

[ Upstream commit 0eb96bf754d7fa6635aa0b0f6650c74b8a6b1cc9 ] This patch fixes the cause of an WARNING indicatng TCP has pending retransmission in Open state in tcp_fastretrans_alert(). The root cause is a bad interaction between path mtu probing, if enabled, and the RACK loss detection. Upong receiving a SACK above the sequence of the MTU probing packet, RACK could mark the probe packet lost in tcp_fastretrans_alert(), prior to calling tcp_simple_retransmit(). tcp_simple_retransmit() only enters Loss state if it newly marks the probe packet lost. If the probe packet is already identified as lost by RACK, the sender remains in Open state with some packets marked lost and retransmitted. Then the next SACK would trigger the warning. The likely scenario is that the probe packet was lost due to its size or network congestion. The actual impact of this warning is small by potentially entering fast recovery an ACK later. The simple fix is always entering recovery (Loss) state if some packet is marked lost during path MTU probing. Fixes: a0370b3f3f2c ("tcp: enable RACK loss detection to trigger recovery") Reported-by: Oleksandr Natalenko Reported-by: Alexei Starovoitov Reported-by: Roman Gushchin Signed-off-by: Yuchung Cheng Reviewed-by: Eric Dumazet Acked-by: Neal Cardwell Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp: gso: avoid refcount_t warning from tcp_gso_segment()

2017-11-24T07:35:56+00:00

[ Upstream commit 7ec318feeed10a64c0359ec4d10889cb4defa39a ] When a GSO skb of truesize O is segmented into 2 new skbs of truesize N1 and N2, we want to transfer socket ownership to the new fresh skbs. In order to avoid expensive atomic operations on a cache line subject to cache bouncing, we replace the sequence : refcount_add(N1, &sk->sk_wmem_alloc); refcount_add(N2, &sk->sk_wmem_alloc); // repeated by number of segments refcount_sub(O, &sk->sk_wmem_alloc); by a single refcount_add(sum_of(N) - O, &sk->sk_wmem_alloc); Problem is : In some pathological cases, sum(N) - O might be a negative number, and syzkaller bot was apparently able to trigger this trace [1] atomic_t was ok with this construct, but we need to take care of the negative delta with refcount_t [1] refcount_t: saturated; leaking memory. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 8404 at lib/refcount.c:77 refcount_add_not_zero+0x198/0x200 lib/refcount.c:77 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 8404 Comm: syz-executor2 Not tainted 4.14.0-rc5-mm1+ #20 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:52 panic+0x1e4/0x41c kernel/panic.c:183 __warn+0x1c4/0x1e0 kernel/panic.c:546 report_bug+0x211/0x2d0 lib/bug.c:183 fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:177 do_trap_no_signal arch/x86/kernel/traps.c:211 [inline] do_trap+0x260/0x390 arch/x86/kernel/traps.c:260 do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:297 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:310 invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905 RIP: 0010:refcount_add_not_zero+0x198/0x200 lib/refcount.c:77 RSP: 0018:ffff8801c606e3a0 EFLAGS: 00010282 RAX: 0000000000000026 RBX: 0000000000001401 RCX: 0000000000000000 RDX: 0000000000000026 RSI: ffffc900036fc000 RDI: ffffed0038c0dc68 RBP: ffff8801c606e430 R08: 0000000000000001 R09: 0000000000000000 R10: ffff8801d97f5eba R11: 0000000000000000 R12: ffff8801d5acf73c R13: 1ffff10038c0dc75 R14: 00000000ffffffff R15: 00000000fffff72f refcount_add+0x1b/0x60 lib/refcount.c:101 tcp_gso_segment+0x10d0/0x16b0 net/ipv4/tcp_offload.c:155 tcp4_gso_segment+0xd4/0x310 net/ipv4/tcp_offload.c:51 inet_gso_segment+0x60c/0x11c0 net/ipv4/af_inet.c:1271 skb_mac_gso_segment+0x33f/0x660 net/core/dev.c:2749 __skb_gso_segment+0x35f/0x7f0 net/core/dev.c:2821 skb_gso_segment include/linux/netdevice.h:3971 [inline] validate_xmit_skb+0x4ba/0xb20 net/core/dev.c:3074 __dev_queue_xmit+0xe49/0x2070 net/core/dev.c:3497 dev_queue_xmit+0x17/0x20 net/core/dev.c:3538 neigh_hh_output include/net/neighbour.h:471 [inline] neigh_output include/net/neighbour.h:479 [inline] ip_finish_output2+0xece/0x1460 net/ipv4/ip_output.c:229 ip_finish_output+0x85e/0xd10 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:238 [inline] ip_output+0x1cc/0x860 net/ipv4/ip_output.c:405 dst_output include/net/dst.h:459 [inline] ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124 ip_queue_xmit+0x8c6/0x18e0 net/ipv4/ip_output.c:504 tcp_transmit_skb+0x1ab7/0x3840 net/ipv4/tcp_output.c:1137 tcp_write_xmit+0x663/0x4de0 net/ipv4/tcp_output.c:2341 __tcp_push_pending_frames+0xa0/0x250 net/ipv4/tcp_output.c:2513 tcp_push_pending_frames include/net/tcp.h:1722 [inline] tcp_data_snd_check net/ipv4/tcp_input.c:5050 [inline] tcp_rcv_established+0x8c7/0x18a0 net/ipv4/tcp_input.c:5497 tcp_v4_do_rcv+0x2ab/0x7d0 net/ipv4/tcp_ipv4.c:1460 sk_backlog_rcv include/net/sock.h:909 [inline] __release_sock+0x124/0x360 net/core/sock.c:2264 release_sock+0xa4/0x2a0 net/core/sock.c:2776 tcp_sendmsg+0x3a/0x50 net/ipv4/tcp.c:1462 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763 sock_sendmsg_nosec net/socket.c:632 [inline] sock_sendmsg+0xca/0x110 net/socket.c:642 ___sys_sendmsg+0x31c/0x890 net/socket.c:2048 __sys_sendmmsg+0x1e6/0x5f0 net/socket.c:2138 Fixes: 14afee4b6092 ("net: convert sock.sk_wmem_alloc from atomic_t to refcount_t") Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp: do not mangle skb->cb[] in tcp_make_synack()

2017-11-24T07:35:55+00:00

[ Upstream commit 3b11775033dc87c3d161996c54507b15ba26414a ] Christoph Paasch sent a patch to address the following issue : tcp_make_synack() is leaving some TCP private info in skb->cb[], then send the packet by other means than tcp_transmit_skb() tcp_transmit_skb() makes sure to clear skb->cb[] to not confuse IPv4/IPV6 stacks, but we have no such cleanup for SYNACK. tcp_make_synack() should not use tcp_init_nondata_skb() : tcp_init_nondata_skb() really should be limited to skbs put in write/rtx queues (the ones that are only sent via tcp_transmit_skb()) This patch fixes the issue and should even save few cpu cycles ;) Fixes: 971f10eca186 ("tcp: better TCP_SKB_CB layout to reduce cache line misses") Signed-off-by: Eric Dumazet Reported-by: Christoph Paasch Reviewed-by: Christoph Paasch Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp_nv: fix division by zero in tcpnv_acked()

2017-11-24T07:35:55+00:00

[ Upstream commit 4eebff27ca4182bbf5f039dd60d79e2d7c0a707e ] Average RTT could become zero. This happened in real life at least twice. This patch treats zero as 1us. Signed-off-by: Konstantin Khlebnikov Acked-by: Lawrence Brakmo Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp: fix tcp_mtu_probe() vs highest_sack

2017-11-18T10:30:39+00:00

[ Upstream commit 2b7cda9c35d3b940eb9ce74b30bbd5eb30db493d ] Based on SNMP values provided by Roman, Yuchung made the observation that some crashes in tcp_sacktag_walk() might be caused by MTU probing. Looking at tcp_mtu_probe(), I found that when a new skb was placed in front of the write queue, we were not updating tcp highest sack. If one skb is freed because all its content was copied to the new skb (for MTU probing), then tp->highest_sack could point to a now freed skb. Bad things would then happen, including infinite loops. This patch renames tcp_highest_sack_combine() and uses it from tcp_mtu_probe() to fix the bug. Note that I also removed one test against tp->sacked_out, since we want to replace tp->highest_sack regardless of whatever condition, since keeping a stale pointer to freed skb is a recipe for disaster. Fixes: a47e5a988a57 ("[TCP]: Convert highest_sack to sk_buff to allow direct access") Signed-off-by: Eric Dumazet Reported-by: Alexei Starovoitov Reported-by: Roman Gushchin Reported-by: Oleksandr Natalenko Acked-by: Alexei Starovoitov Acked-by: Neal Cardwell Acked-by: Yuchung Cheng Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp: refresh tp timestamp before tcp_mtu_probe()

2017-11-18T10:30:38+00:00

[ Upstream commit ee1836aec4f5a977c1699a311db4d9027ef21ac8 ] In the unlikely event tcp_mtu_probe() is sending a packet, we want tp->tcp_mstamp being as accurate as possible. This means we need to call tcp_mstamp_refresh() a bit earlier in tcp_write_xmit(). Fixes: 385e20706fac ("tcp: use tp->tcp_mstamp in output path") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

ipip: only increase err_count for some certain type icmp in ipip_err

2017-11-18T10:30:38+00:00

[ Upstream commit f3594f0a7ea36661d7fd942facd7f31a64245f1a ] t->err_count is used to count the link failure on tunnel and an err will be reported to user socket in tx path if t->err_count is not 0. udp socket could even return EHOSTUNREACH to users. Since commit fd58156e456d ("IPIP: Use ip-tunneling code.") removed the 'switch check' for icmp type in ipip_err(), err_count would be increased by the icmp packet with ICMP_EXC_FRAGTIME code. an link failure would be reported out due to this. In Jianlin's case, when receiving ICMP_EXC_FRAGTIME a icmp packet, udp netperf failed with the err: send_data: data send error: No route to host (errno 113) We expect this error reported from tunnel to socket when receiving some certain type icmp, but not ICMP_EXC_FRAGTIME, ICMP_SR_FAILED or ICMP_PARAMETERPROB ones. This patch is to bring 'switch check' for icmp type back to ipip_err so that it only reports link failure for the right type icmp, just as in ipgre_err() and ipip6_err(). Fixes: fd58156e456d ("IPIP: Use ip-tunneling code.") Reported-by: Jianlin Shi Signed-off-by: Xin Long Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp/dccp: fix other lockdep splats accessing ireq_opt

2017-11-18T10:30:37+00:00

[ Upstream commit 06f877d613be3621604c2520ec0351d9fbdca15f ] In my first attempt to fix the lockdep splat, I forgot we could enter inet_csk_route_req() with a freshly allocated request socket, for which refcount has not yet been elevated, due to complex SLAB_TYPESAFE_BY_RCU rules. We either are in rcu_read_lock() section _or_ we own a refcount on the request. Correct RCU verb to use here is rcu_dereference_check(), although it is not possible to prove we actually own a reference on a shared refcount :/ In v2, I added ireq_opt_deref() helper and use in three places, to fix other possible splats. [ 49.844590] lockdep_rcu_suspicious+0xea/0xf3 [ 49.846487] inet_csk_route_req+0x53/0x14d [ 49.848334] tcp_v4_route_req+0xe/0x10 [ 49.850174] tcp_conn_request+0x31c/0x6a0 [ 49.851992] ? __lock_acquire+0x614/0x822 [ 49.854015] tcp_v4_conn_request+0x5a/0x79 [ 49.855957] ? tcp_v4_conn_request+0x5a/0x79 [ 49.858052] tcp_rcv_state_process+0x98/0xdcc [ 49.859990] ? sk_filter_trim_cap+0x2f6/0x307 [ 49.862085] tcp_v4_do_rcv+0xfc/0x145 [ 49.864055] ? tcp_v4_do_rcv+0xfc/0x145 [ 49.866173] tcp_v4_rcv+0x5ab/0xaf9 [ 49.868029] ip_local_deliver_finish+0x1af/0x2e7 [ 49.870064] ip_local_deliver+0x1b2/0x1c5 [ 49.871775] ? inet_del_offload+0x45/0x45 [ 49.873916] ip_rcv_finish+0x3f7/0x471 [ 49.875476] ip_rcv+0x3f1/0x42f [ 49.876991] ? ip_local_deliver_finish+0x2e7/0x2e7 [ 49.878791] __netif_receive_skb_core+0x6d3/0x950 [ 49.880701] ? process_backlog+0x7e/0x216 [ 49.882589] __netif_receive_skb+0x1d/0x5e [ 49.884122] process_backlog+0x10c/0x216 [ 49.885812] net_rx_action+0x147/0x3df Fixes: a6ca7abe53633 ("tcp/dccp: fix lockdep splat in inet_csk_route_req()") Fixes: c92e8c02fe66 ("tcp/dccp: fix ireq->opt races") Signed-off-by: Eric Dumazet Reported-by: kernel test robot Reported-by: Maciej Żenczykowski Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp/dccp: fix lockdep splat in inet_csk_route_req()

2017-11-18T10:30:37+00:00

[ Upstream commit a6ca7abe53633d08eea1c6756cb49c9b2d4c90bf ] This patch fixes the following lockdep splat in inet_csk_route_req() lockdep_rcu_suspicious inet_csk_route_req tcp_v4_send_synack tcp_rtx_synack inet_rtx_syn_ack tcp_fastopen_synack_time tcp_retransmit_timer tcp_write_timer_handler tcp_write_timer call_timer_fn Thread running inet_csk_route_req() owns a reference on the request socket, so we have the guarantee ireq->ireq_opt wont be changed or freed. lockdep can enforce this invariant for us. Fixes: c92e8c02fe66 ("tcp/dccp: fix ireq->opt races") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

soreuseport: fix initialization race

2017-11-18T10:30:37+00:00

[ Upstream commit 1b5f962e71bfad6284574655c406597535c3ea7a ] Syzkaller stumbled upon a way to trigger WARNING: CPU: 1 PID: 13881 at net/core/sock_reuseport.c:41 reuseport_alloc+0x306/0x3b0 net/core/sock_reuseport.c:39 There are two initialization paths for the sock_reuseport structure in a socket: Through the udp/tcp bind paths of SO_REUSEPORT sockets or through SO_ATTACH_REUSEPORT_[CE]BPF before bind. The existing implementation assumedthat the socket lock protected both of these paths when it actually only protects the SO_ATTACH_REUSEPORT path. Syzkaller triggered this double allocation by running these paths concurrently. This patch moves the check for double allocation into the reuseport_alloc function which is protected by a global spin lock. Fixes: e32ea7e74727 ("soreuseport: fast reuseport UDP socket selection") Fixes: c125e80b8868 ("soreuseport: fast reuseport TCP socket selection") Signed-off-by: Craig Gallek Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman