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linux/net/ipv4
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Neal Cardwell dad8cea7ad tcp: fix TFO SYNACK undo to avoid double-timestamp-undo 
In a rare corner case the new logic for undo of SYNACK RTO could
result in triggering the warning in tcp_fastretrans_alert() that says:
        WARN_ON(tp->retrans_out != 0);

The warning looked like:

WARNING: CPU: 1 PID: 1 at net/ipv4/tcp_input.c:2818 tcp_ack+0x13e0/0x3270

The sequence that tickles this bug is:
 - Fast Open server receives TFO SYN with data, sends SYNACK
 - (client receives SYNACK and sends ACK, but ACK is lost)
 - server app sends some data packets
 - (N of the first data packets are lost)
 - server receives client ACK that has a TS ECR matching first SYNACK,
   and also SACKs suggesting the first N data packets were lost
    - server performs TS undo of SYNACK RTO, then immediately
      enters recovery
    - buggy behavior then performed a *second* undo that caused
      the connection to be in CA_Open with retrans_out != 0

Basically, the incoming ACK packet with SACK blocks causes us to first
undo the cwnd reduction from the SYNACK RTO, but then immediately
enters fast recovery, which then makes us eligible for undo again. And
then tcp_rcv_synrecv_state_fastopen() accidentally performs an undo
using a "mash-up" of state from two different loss recovery phases: it
uses the timestamp info from the ACK of the original SYNACK, and the
undo_marker from the fast recovery.

This fix refines the logic to only invoke the tcp_try_undo_loss()
inside tcp_rcv_synrecv_state_fastopen() if the connection is still in
CA_Loss.  If peer SACKs triggered fast recovery, then
tcp_rcv_synrecv_state_fastopen() can't safely undo.

Fixes: 794200d662 ("tcp: undo cwnd on Fast Open spurious SYNACK retransmit")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-23 17:23:35 -08:00
..
bpfilter SPDX update for 5.2-rc2, round 1 2019-05-21 12:33:38 -07:00
netfilter proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
af_inet.c net: port < inet_prot_sock(net) --> inet_port_requires_bind_service(net, port) 2019-11-26 13:20:46 -08:00
ah4.c xfrm: remove type and offload_type map from xfrm_state_afinfo 2019-06-06 08:34:50 +02:00
arp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
bpf_tcp_ca.c bpf: Add BPF_FUNC_tcp_send_ack helper 2020-01-09 08:46:18 -08:00
cipso_ipv4.c ipv4: ensure rcu_read_lock() in cipso_v4_error() 2020-02-22 21:45:55 -08:00
datagram.c inet: stop leaking jiffies on the wire 2019-11-01 14:57:52 -07:00
devinet.c inet: protect against too small mtu values. 2019-12-07 11:55:11 -08:00
esp4_offload.c xfrm: support output_mark for offload ESP packets 2020-01-15 12:18:35 +01:00
esp4.c xfrm: add espintcp (RFC 8229) 2019-12-09 09:59:07 +01:00
fib_frontend.c ipv4: move fib4_has_custom_rules() helper to public header 2019-11-21 14:45:55 -08:00
fib_lookup.h ipv4: Add "offload" and "trap" indications to routes 2020-01-14 18:53:35 -08:00
fib_notifier.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fib_rules.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fib_semantics.c ipv4: Add "offload" and "trap" indications to routes 2020-01-14 18:53:35 -08:00
fib_trie.c Merge ra.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2020-01-19 22:10:04 +01:00
fou.c fou: Fix IPv6 netlink policy 2020-01-23 14:32:52 +01:00
gre_demux.c gre: refetch erspan header from skb->data after pskb_may_pull() 2019-12-07 11:53:27 -08:00
gre_offload.c net: remove the check argument from __skb_gro_checksum_convert 2020-01-03 12:24:34 -08:00
icmp.c icmp: introduce helper for nat'd source address in network device context 2020-02-13 14:19:00 -08:00
igmp.c igmp: uninline ip_mc_validate_checksum() 2019-10-04 14:26:46 -07:00
inet_connection_sock.c tcp/ipv4: remove AF_INET_FAMILY 2020-01-21 12:03:51 +01:00
inet_diag.c tcp/dccp: fix possible race __inet_lookup_established() 2019-12-13 21:40:49 -08:00
inet_fragment.c inet: frags: re-introduce skb coalescing for local delivery 2019-08-08 15:55:10 -07:00
inet_hashtables.c tcp/dccp: fix possible race __inet_lookup_established() 2019-12-13 21:40:49 -08:00
inet_timewait_sock.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
inetpeer.c inetpeer: fix data-race in inet_putpeer / inet_putpeer 2019-11-07 16:15:56 -08:00
ip_forward.c ipv4: Revert removal of rt_uses_gateway 2019-09-20 18:23:33 -07:00
ip_fragment.c inet: frags: re-introduce skb coalescing for local delivery 2019-08-08 15:55:10 -07:00
ip_gre.c treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
ip_input.c ipv4: use dst hint for ipv4 list receive 2019-11-21 14:45:55 -08:00
ip_options.c netfilter: nf_tables: add support for matching IPv4 options 2019-06-21 18:35:51 +02:00
ip_output.c net: ipv4: use skb_list_walk_safe helper for gso segments 2020-01-14 11:48:41 -08:00
ip_sockglue.c ip_sockglue: Fix missing-check bug in ip_ra_control() 2019-05-25 11:00:50 -07:00
ip_tunnel_core.c lwtunnel: check erspan options before allocating tun_info 2019-11-21 11:47:39 -08:00
ip_tunnel.c net, ip_tunnel: fix namespaces move 2020-01-21 16:05:21 +01:00
ip_vti.c vti[6]: fix packet tx through bpf_redirect() 2020-01-14 08:55:38 +01:00
ipcomp.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2019-07-05 15:01:15 -07:00
ipconfig.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
ipip.c ipip: validate header length in ipip_tunnel_xmit 2019-07-25 17:23:40 -07:00
ipmr_base.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
ipmr.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-16 21:51:42 -08:00
Kconfig xfrm: add espintcp (RFC 8229) 2019-12-09 09:59:07 +01:00
Makefile bpf: tcp: Support tcp_congestion_ops in bpf 2020-01-09 08:46:18 -08:00
metrics.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
netfilter.c netfilter: ipv4: remove useless export_symbol 2019-01-28 11:32:58 +01:00
netlink.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
nexthop.c net: include struct nhmsg size in nh nlmsg size 2020-01-27 10:54:08 +01:00
ping.c ip: support SO_MARK cmsg 2019-09-13 21:44:19 +02:00
proc.c tcp: export count for rehash attempts 2020-01-26 15:28:47 +01:00
protocol.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
raw_diag.c net: don't warn in inet diag when IPV6 is disabled 2019-07-03 11:26:35 -07:00
raw.c netfilter: drop bridge nf reset from nf_reset 2019-10-01 18:42:15 +02:00
route.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
syncookies.c mptcp: handle tcp fallback when using syn cookies 2020-01-29 17:45:20 +01:00
sysctl_net_ipv4.c net-tcp: Disable TCP ssthresh metrics cache by default 2019-12-09 20:17:48 -08:00
tcp_bbr.c tcp_bbr: improve arithmetic division in bbr_update_bw() 2020-01-21 10:45:49 +01:00
tcp_bic.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_bpf.c bpf: Sockmap/tls, fix pop data with SK_DROP return code 2020-01-15 23:26:13 +01:00
tcp_cdg.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_cong.c bpf: tcp: Support tcp_congestion_ops in bpf 2020-01-09 08:46:18 -08:00
tcp_cubic.c tcp_cubic: refactor code to perform a divide only when needed 2019-12-30 14:44:27 -08:00
tcp_dctcp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
tcp_dctcp.h tcp: refactor DCTCP ECN ACK handling 2018-10-10 22:26:00 -07:00
tcp_diag.c net: annotate lockless accesses to sk->sk_max_ack_backlog 2019-11-06 16:14:48 -08:00
tcp_fastopen.c tcp: add TCP_INFO status for failed client TFO 2019-10-25 19:25:37 -07:00
tcp_highspeed.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_htcp.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_hybla.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_illinois.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_input.c tcp: fix TFO SYNACK undo to avoid double-timestamp-undo 2020-02-23 17:23:35 -08:00
tcp_ipv4.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-01-23 08:10:16 +01:00
tcp_lp.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_metrics.c net-tcp: Disable TCP ssthresh metrics cache by default 2019-12-09 20:17:48 -08:00
tcp_minisocks.c bpf: tcp: Support tcp_congestion_ops in bpf 2020-01-09 08:46:18 -08:00
tcp_nv.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_offload.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
tcp_output.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-26 10:40:21 +01:00
tcp_rate.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
tcp_recovery.c tcp: introduce tcp_skb_timestamp_us() helper 2018-09-21 19:37:59 -07:00
tcp_scalable.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_timer.c tcp: export count for rehash attempts 2020-01-26 15:28:47 +01:00
tcp_ulp.c bpf: Sockmap/tls, push write_space updates through ulp updates 2020-01-15 23:26:13 +01:00
tcp_vegas.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_vegas.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
tcp_veno.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_westwood.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_yeah.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp.c tcp: clear tp->segs_{in|out} in tcp_disconnect() 2020-01-31 22:12:37 -08:00
tunnel4.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
udp_diag.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
udp_impl.h udp: add missing rehash callback to udplite 2019-01-17 15:01:08 -08:00
udp_offload.c udp: Support UDP fraglist GRO/GSO. 2020-01-27 11:00:21 +01:00
udp_tunnel.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
udp.c udp: rehash on disconnect 2020-02-19 16:34:11 -08:00
udplite.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
xfrm4_input.c xfrm: reset transport header back to network header after all input transforms ahave been applied 2018-09-04 10:26:30 +02:00
xfrm4_output.c netfilter: Support iif matches in POSTROUTING 2019-11-15 23:44:48 +01:00
xfrm4_policy.c net: add bool confirm_neigh parameter for dst_ops.update_pmtu 2019-12-24 22:28:54 -08:00
xfrm4_protocol.c xfrm: add route lookup to xfrm4_rcv_encap 2019-12-09 09:59:07 +01:00
xfrm4_state.c xfrm: remove eth_proto value from xfrm_state_afinfo 2019-06-06 08:34:50 +02:00
xfrm4_tunnel.c xfrm: remove type and offload_type map from xfrm_state_afinfo 2019-06-06 08:34:50 +02:00