Yuchung Cheng 8b8a321ff7 tcp: fix zero cwnd in tcp_cwnd_reduction ... Patch 3759824da8 ("tcp: PRR uses CRB mode by default and SS mode conditionally") introduced a bug that cwnd may become 0 when both inflight and sndcnt are 0 (cwnd = inflight + sndcnt). This may lead to a div-by-zero if the connection starts another cwnd reduction phase by setting tp->prior_cwnd to the current cwnd (0) in tcp_init_cwnd_reduction(). To prevent this we skip PRR operation when nothing is acked or sacked. Then cwnd must be positive in all cases as long as ssthresh is positive: 1) The proportional reduction mode inflight > ssthresh > 0 2) The reduction bound mode a) inflight == ssthresh > 0 b) inflight < ssthresh sndcnt > 0 since newly_acked_sacked > 0 and inflight < ssthresh Therefore in all cases inflight and sndcnt can not both be 0. We check invalid tp->prior_cwnd to avoid potential div0 bugs. In reality this bug is triggered only with a sequence of less common events. For example, the connection is terminating an ECN-triggered cwnd reduction with an inflight 0, then it receives reordered/old ACKs or DSACKs from prior transmission (which acks nothing). Or the connection is in fast recovery stage that marks everything lost, but fails to retransmit due to local issues, then receives data packets from other end which acks nothing. Fixes: 3759824da8 ("tcp: PRR uses CRB mode by default and SS mode conditionally") Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2016-01-06 16:39:56 -05:00
..
netfilter	netfilter: nf_dup: add missing dependencies with NF_CONNTRACK	2015-12-10 18:17:06 +01:00
Kconfig	geneve: Consolidate Geneve functionality in single module.	2015-08-27 15:42:48 -07:00
Makefile	tcp: track the packet timings in RACK	2015-10-21 07:00:48 -07:00
af_inet.c	net: add validation for the socket syscall protocol argument	2015-12-14 16:09:30 -05:00
ah4.c	ah4: Fix error return in ah_input().	2015-08-25 13:38:50 -07:00
arp.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2015-10-20 06:08:27 -07:00
cipso_ipv4.c	ipv4: coding style: comparison for inequality with NULL	2015-04-03 12:11:15 -04:00
datagram.c	net: Set sk_txhash from a random number	2015-07-29 22:44:04 -07:00
devinet.c	netlink: Rightsize IFLA_AF_SPEC size calculation	2015-10-21 19:15:20 -07:00
esp4.c	esp4: Switch to new AEAD interface	2015-05-28 11:23:20 +08:00
fib_frontend.c	net: Flush local routes when device changes vrf association	2015-12-13 23:58:44 -05:00
fib_lookup.h	ipv4: consider TOS in fib_select_default	2015-07-24 22:46:11 -07:00
fib_rules.c	net: ipv6: use common fib_default_rule_pref	2015-09-09 14:19:50 -07:00
fib_semantics.c	net: Fix prefsrc lookups	2015-11-04 21:34:37 -05:00
fib_trie.c	fib_trie: leaf_walk_rcu should not compute key if key is less than pn->key	2015-10-27 18:14:51 -07:00
fou.c	fou: clean up socket with kfree_rcu	2015-12-16 19:03:02 -05:00
gre_demux.c	gre: Remove support for sharing GRE protocol hook.	2015-08-10 14:03:54 -07:00
gre_offload.c	ipv6: gre: support SIT encapsulation	2015-10-26 22:01:18 -07:00
icmp.c	Revert "ipv4/icmp: redirect messages can use the ingress daddr as source"	2015-10-14 06:01:07 -07:00
igmp.c	ipv4: igmp: Allow removing groups from a removed interface	2015-12-03 12:07:05 -05:00
inet_connection_sock.c	tcp: ensure proper barriers in lockless contexts	2015-11-15 18:36:38 -05:00
inet_diag.c	tcp/dccp: install syn_recv requests into ehash table	2015-10-03 04:32:41 -07:00
inet_fragment.c	net: fix percpu memory leaks	2015-11-02 22:47:14 -05:00
inet_hashtables.c	tcp/dccp: fix hashdance race for passive sessions	2015-10-23 05:42:21 -07:00
inet_lro.c	lro: remove dead code	2013-12-29 16:34:25 -05:00
inet_timewait_sock.c	tcp/dccp: fix timewait races in timer handling	2015-09-21 16:32:29 -07:00
inetpeer.c	net: Add helper function to compare inetpeer addresses	2015-08-28 13:32:36 -07:00
ip_forward.c	net: Pass net into dst_output and remove dst_output_okfn	2015-10-08 04:26:54 -07:00
ip_fragment.c	net: fix percpu memory leaks	2015-11-02 22:47:14 -05:00
ip_gre.c	openvswitch: Fix egress tunnel info.	2015-10-22 19:39:25 -07:00
ip_input.c	ipv4: Pass struct net into ip_defrag and ip_check_defrag	2015-10-12 19:44:16 -07:00
ip_options.c	ipv4: coding style: comparison for inequality with NULL	2015-04-03 12:11:15 -04:00
ip_output.c	ipv4: add defensive check for CHECKSUM_PARTIAL skbs in ip_fragment	2015-11-01 12:01:27 -05:00
ip_sockglue.c	ipv4: fix a potential deadlock in mcast getsockopt() path	2015-11-04 21:29:59 -05:00
ip_tunnel.c	ip_gre: Add support to collect tunnel metadata.	2015-08-10 14:03:54 -07:00
ip_tunnel_core.c	ipv4, ipv6: Pass net into ip_local_out and ip6_local_out	2015-10-08 04:27:02 -07:00
ip_vti.c	net: Pass net into dst_output and remove dst_output_okfn	2015-10-08 04:26:54 -07:00
ipcomp.c	ipv4: coding style: comparison for equality with NULL	2015-04-03 12:11:15 -04:00
ipconfig.c	ipconfig: send Client-identifier in DHCP requests	2015-10-18 19:23:52 -07:00
ipip.c	ipip: ioctl: Remove superfluous IP-TTL handling.	2015-12-18 16:07:59 -05:00
ipmr.c	net: ipmr, ip6mr: fix vif/tunnel failure race condition	2015-11-24 17:15:56 -05:00
netfilter.c	ipv4: Pass struct net into ip_route_me_harder	2015-09-29 20:21:32 +02:00
ping.c	ipv6: Nonlocal bind	2015-07-09 21:09:10 -07:00
proc.c	net: track success and failure of TCP PMTU probing	2015-07-21 22:36:33 -07:00
protocol.c	net: Export inet_offloads and inet6_offloads	2014-09-19 17:15:31 -04:00
raw.c	net: Propagate lookup failure in l3mdev_get_saddr to caller	2016-01-04 22:58:30 -05:00
route.c	net: Do not drop to make_route if oif is l3mdev	2015-10-08 05:18:47 -07:00
syncookies.c	tcp/dccp: fix hashdance race for passive sessions	2015-10-23 05:42:21 -07:00
sysctl_net_ipv4.c	ipv4: disable BH when changing ip local port range	2015-11-04 21:29:06 -05:00
tcp.c	net: rename SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA	2015-12-01 15:45:05 -05:00
tcp_bic.c	tcp: add tcp_in_slow_start helper	2015-07-09 14:22:52 -07:00
tcp_cdg.c	tcp: do not slow start when cwnd equals ssthresh	2015-07-09 14:22:52 -07:00
tcp_cong.c	tcp: remove tcp_ecn_make_synack() socket argument	2015-09-25 13:00:38 -07:00
tcp_cubic.c	tcp_cubic: do not set epoch_start in the future	2015-09-17 22:35:07 -07:00
tcp_dctcp.c	tcp: allow dctcp alpha to drop to zero	2015-10-23 02:46:52 -07:00
tcp_diag.c	tcp: ensure proper barriers in lockless contexts	2015-11-15 18:36:38 -05:00
tcp_fastopen.c	tcp/dccp: fix hashdance race for passive sessions	2015-10-23 05:42:21 -07:00
tcp_highspeed.c	tcp: add tcp_in_slow_start helper	2015-07-09 14:22:52 -07:00
tcp_htcp.c	tcp: add tcp_in_slow_start helper	2015-07-09 14:22:52 -07:00
tcp_hybla.c	tcp: do not slow start when cwnd equals ssthresh	2015-07-09 14:22:52 -07:00
tcp_illinois.c	tcp: add tcp_in_slow_start helper	2015-07-09 14:22:52 -07:00
tcp_input.c	tcp: fix zero cwnd in tcp_cwnd_reduction	2016-01-06 16:39:56 -05:00
tcp_ipv4.c	net: fix IP early demux races	2015-12-14 23:52:00 -05:00
tcp_lp.c	tcp: remove in_flight parameter from cong_avoid() methods	2014-05-03 19:23:07 -04:00
tcp_memcontrol.c	memcg: cleanup static keys decrement	2015-02-12 18:54:10 -08:00
tcp_metrics.c	net: Add helper function to compare inetpeer addresses	2015-08-28 13:32:36 -07:00
tcp_minisocks.c	tcp: fix req->saved_syn race	2015-11-05 14:36:09 -05:00
tcp_offload.c	tcp: reserve tcp_skb_mss() to tcp stack	2015-06-11 16:33:10 -07:00
tcp_output.c	tcp: restore fastopen with no data in SYN packet	2015-12-17 15:37:39 -05:00
tcp_probe.c	tcp: whitespace fixes	2014-09-01 18:12:45 -07:00
tcp_recovery.c	tcp: use RACK to detect losses	2015-10-21 07:00:53 -07:00
tcp_scalable.c	tcp: add tcp_in_slow_start helper	2015-07-09 14:22:52 -07:00
tcp_timer.c	tcp: fix Fast Open snmp over-counting bug	2015-11-20 10:51:12 -05:00
tcp_vegas.c	tcp: add tcp_in_slow_start helper	2015-07-09 14:22:52 -07:00
tcp_vegas.h	tcp: prepare CC get_info() access from getsockopt()	2015-04-29 17:10:38 -04:00
tcp_veno.c	tcp: add tcp_in_slow_start helper	2015-07-09 14:22:52 -07:00
tcp_westwood.c	tcp_westwood: fix tcp_westwood_info()	2015-05-05 19:50:09 -04:00
tcp_yeah.c	tcp: stretch ACK fixes prep	2015-01-28 22:18:37 -08:00
tunnel4.c	net: Convert printks to pr_<level>	2012-03-11 23:42:51 -07:00
udp.c	net: Propagate lookup failure in l3mdev_get_saddr to caller	2016-01-04 22:58:30 -05:00
udp_diag.c	sock_diag: specify info_size per inet protocol	2015-06-15 19:49:22 -07:00
udp_impl.h	net: Remove iocb argument from sendmsg and recvmsg	2015-03-02 13:06:31 -05:00
udp_offload.c	ipv4: coding style: comparison for inequality with NULL	2015-04-03 12:11:15 -04:00
udp_tunnel.c	tunnel: introduce udp_tun_rx_dst()	2015-08-27 15:42:47 -07:00
udplite.c	net: Eliminate no_check from protosw	2014-05-23 16:28:53 -04:00
xfrm4_input.c	netfilter: Pass net into okfn	2015-09-17 17:18:37 -07:00
xfrm4_mode_beet.c	ipv4: ERROR: code indent should use tabs where possible	2013-12-26 13:43:21 -05:00
xfrm4_mode_transport.c	…
xfrm4_mode_tunnel.c	ipv4: hash net ptr into fragmentation bucket selection	2015-03-25 14:07:04 -04:00
xfrm4_output.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2015-10-24 06:54:12 -07:00
xfrm4_policy.c	Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec	2015-12-22 16:26:31 -05:00
xfrm4_protocol.c	xfrm4: Remove duplicate semicolon	2014-06-30 07:49:47 +02:00
xfrm4_state.c	inet: make no_pmtu_disc per namespace and kill ipv4_config	2013-12-18 16:58:20 -05:00
xfrm4_tunnel.c	sit: add IPv4 over IPv4 support	2013-05-31 17:19:05 -07:00