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6de035fec0
linux/net/ipv4
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Neal Cardwell 6de035fec0 tcp_bbr: fix u32 wrap bug in round logic if bbr_init() called after 2B packets 
Currently if BBR congestion control is initialized after more than 2B
packets have been delivered, depending on the phase of the
tp->delivered counter the tracking of BBR round trips can get stuck.

The bug arises because if tp->delivered is between 2^31 and 2^32 at
the time the BBR congestion control module is initialized, then the
initialization of bbr->next_rtt_delivered to 0 will cause the logic to
believe that the end of the round trip is still billions of packets in
the future. More specifically, the following check will fail
repeatedly:

  !before(rs->prior_delivered, bbr->next_rtt_delivered)

and thus the connection will take up to 2B packets delivered before
that check will pass and the connection will set:

  bbr->round_start = 1;

This could cause many mechanisms in BBR to fail to trigger, for
example bbr_check_full_bw_reached() would likely never exit STARTUP.

This bug is 5 years old and has not been observed, and as a practical
matter this would likely rarely trigger, since it would require
transferring at least 2B packets, or likely more than 3 terabytes of
data, before switching congestion control algorithms to BBR.

This patch is a stable candidate for kernels as far back as v4.9,
when tcp_bbr.c was added.

Fixes: 0f8782ea14 ("tcp_bbr: add BBR congestion control")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Kevin Yang <yyd@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20210811024056.235161-1-ncardwell@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-08-11 15:00:15 -07:00
..
bpfilter net: Revert "net: optimize the sockptr_t for unified kernel/user address spaces" 2020-08-10 12:06:44 -07:00
netfilter netfilter: nf_tables: add and use nft_sk helper 2021-05-29 01:04:53 +02:00
af_inet.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-06-18 19:47:02 -07:00
ah4.c Networking changes for 5.14. 2021-06-30 15:51:09 -07:00
arp.c net: Exempt multicast addresses from five-second neighbor lifetime 2020-11-13 14:24:39 -08:00
bpf_tcp_ca.c bpf: Limit static tcp-cc functions in the .BTF_ids list to x86 2021-05-11 23:23:07 +02:00
cipso_ipv4.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-06-18 19:47:02 -07:00
datagram.c
devinet.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-06-18 19:47:02 -07:00
esp4_offload.c xfrm: remove description from xfrm_type struct 2021-06-09 09:38:52 +02:00
esp4.c Networking changes for 5.14. 2021-06-30 15:51:09 -07:00
fib_frontend.c net: Use nlmsg_unicast() instead of netlink_unicast() 2021-07-13 09:28:29 -07:00
fib_lookup.h ipv4: Fix spelling mistakes 2021-06-07 14:08:30 -07:00
fib_notifier.c
fib_rules.c fib: use indirect call wrappers in the most common fib_rules_ops 2020-07-28 17:42:31 -07:00
fib_semantics.c ipv4: Fix fall-through warnings for Clang 2021-05-17 19:29:10 -05:00
fib_trie.c IPv4: Extend 'fib_notify_on_flag_change' sysctl 2021-02-08 16:47:03 -08:00
fou.c genetlink: move to smaller ops wherever possible 2020-10-02 19:11:11 -07:00
gre_demux.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
gre_offload.c ip_gre: add csum offload support for gre header 2021-01-29 20:39:14 -08:00
icmp.c ipv6: ICMPV6: add response to ICMPV6 RFC 8335 PROBE messages 2021-06-28 14:29:45 -07:00
igmp.c net: igmp: fix data-race in igmp_ifc_timer_expire() 2021-08-10 11:56:52 +01:00
inet_connection_sock.c tcp: Add stats for socket migration. 2021-06-23 12:56:08 -07:00
inet_diag.c net: Use nlmsg_unicast() instead of netlink_unicast() 2021-07-13 09:28:29 -07:00
inet_fragment.c inet: frags: batch fqdir destroy works 2020-12-12 15:08:54 -08:00
inet_hashtables.c tcp: Keep TCP_CLOSE sockets in the reuseport group. 2021-06-15 18:01:05 +02:00
inet_timewait_sock.c net: Use generic ns_common::count 2020-08-19 14:06:36 +02:00
inetpeer.c inetpeer: use div64_ul() and clamp_val() calculate inet_peer_threshold 2021-03-01 13:32:12 -08:00
ip_forward.c
ip_fragment.c
ip_gre.c gre: let mac_header point to outer header only when necessary 2021-06-28 12:44:17 -07:00
ip_input.c net: use indirect call helpers for dst_input 2021-02-03 14:51:39 -08:00
ip_options.c net: clean up codestyle for net/ipv4 2020-08-25 06:28:02 -07:00
ip_output.c net: ip: avoid OOM kills with large UDP sends over loopback 2021-06-24 11:17:21 -07:00
ip_sockglue.c net: Remove duplicated midx check against 0 2020-08-25 06:23:59 -07:00
ip_tunnel_core.c net: ip_tunnel: clean up endianness conversions 2021-01-08 19:25:35 -08:00
ip_tunnel.c net: Set true network header for ECN decapsulation 2021-07-23 16:38:57 +01:00
ip_vti.c ipv4: Fix fall-through warnings for Clang 2021-05-17 19:29:10 -05:00
ipcomp.c Networking changes for 5.14. 2021-06-30 15:51:09 -07:00
ipconfig.c net: ipconfig: Don't override command-line hostnames or domains 2021-06-02 13:27:03 -07:00
ipip.c ipip: allow redirecting ipip and mplsip packets to eth devices 2021-06-28 12:44:17 -07:00
ipmr_base.c
ipmr.c ipmr: Fix indentation issue 2021-07-07 20:52:25 -07:00
Kconfig net: ipv4: remove duplicate "the the" phrase in Kconfig text 2020-08-18 16:02:16 -07:00
Makefile bpf: Clean up sockmap related Kconfigs 2021-02-26 12:28:03 -08:00
metrics.c treewide: rename nla_strlcpy to nla_strscpy. 2020-11-16 08:08:54 -08:00
netfilter.c netfilter: Dissect flow after packet mangling 2021-04-18 22:04:16 +02:00
netlink.c
nexthop.c nexthop: Restart nexthop dump based on last dumped nexthop identifier 2021-04-19 15:20:34 -07:00
ping.c net: sock: introduce sk_error_report 2021-06-29 11:28:21 -07:00
proc.c tcp: Add stats for socket migration. 2021-06-23 12:56:08 -07:00
protocol.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
raw_diag.c net: Use nlmsg_unicast() instead of netlink_unicast() 2021-07-13 09:28:29 -07:00
raw.c net: sock: introduce sk_error_report 2021-06-29 11:28:21 -07:00
route.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-06-29 15:45:27 -07:00
syncookies.c selinux/stable-5.11 PR 20201214 2020-12-16 11:01:04 -08:00
sysctl_net_ipv4.c net: Introduce net.ipv4.tcp_migrate_req. 2021-06-15 18:01:05 +02:00
tcp_bbr.c tcp_bbr: fix u32 wrap bug in round logic if bbr_init() called after 2B packets 2021-08-11 15:00:15 -07:00
tcp_bic.c
tcp_bpf.c bpf, sockmap, tcp: sk_prot needs inuse_idx set for proc stats 2021-07-15 19:54:22 +02:00
tcp_cdg.c
tcp_cong.c net: Only allow init netns to set default tcp cong to a restricted algo 2021-05-04 11:58:28 -07:00
tcp_cubic.c tcp: Rename bictcp function prefix to cubictcp 2021-03-26 20:41:51 -07:00
tcp_dctcp.c
tcp_dctcp.h
tcp_diag.c
tcp_fastopen.c tcp: disable TFO blackhole logic by default 2021-07-21 22:50:31 -07:00
tcp_highspeed.c Replace HTTP links with HTTPS ones: IPv* 2020-07-06 13:23:03 -07:00
tcp_htcp.c Replace HTTP links with HTTPS ones: IPv* 2020-07-06 13:23:03 -07:00
tcp_hybla.c
tcp_illinois.c
tcp_input.c mptcp: avoid processing packet if a subflow reset 2021-07-09 18:38:53 -07:00
tcp_ipv4.c tcp: disable TFO blackhole logic by default 2021-07-21 22:50:31 -07:00
tcp_lp.c ipv4: tcp_lp.c: Couple of typo fixes 2021-03-28 17:31:13 -07:00
tcp_metrics.c fixes-v5.11 2020-12-14 16:40:27 -08:00
tcp_minisocks.c tcp: Add stats for socket migration. 2021-06-23 12:56:08 -07:00
tcp_nv.c
tcp_offload.c net, gro: Set inner transport header offset in tcp/udp GRO hook 2021-08-02 10:20:56 +01:00
tcp_output.c ipv6: tcp: drop silly ICMPv6 packet too big messages 2021-07-08 12:27:08 -07:00
tcp_rate.c
tcp_recovery.c tcp: fix TLP timer not set when CA_STATE changes from DISORDER to OPEN 2021-01-23 21:33:01 -08:00
tcp_scalable.c net: ipv4: delete repeated words 2020-08-24 17:31:20 -07:00
tcp_timer.c net: sock: introduce sk_error_report 2021-06-29 11:28:21 -07:00
tcp_ulp.c
tcp_vegas.c tcp: use semicolons rather than commas to separate statements 2020-10-13 17:11:52 -07:00
tcp_vegas.h
tcp_veno.c Replace HTTP links with HTTPS ones: IPv* 2020-07-06 13:23:03 -07:00
tcp_westwood.c
tcp_yeah.c tcp_yeah: check struct yeah size at compile time 2021-06-29 11:54:36 -07:00
tcp.c tcp: call sk_wmem_schedule before sk_mem_charge in zerocopy path 2021-07-09 11:25:24 -07:00
tunnel4.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
udp_bpf.c bpf, sockmap, udp: sk_prot needs inuse_idx set for proc stats 2021-07-15 19:54:36 +02:00
udp_diag.c net: Use nlmsg_unicast() instead of netlink_unicast() 2021-07-13 09:28:29 -07:00
udp_impl.h net: pass a sockptr_t into ->setsockopt 2020-07-24 15:41:54 -07:00
udp_offload.c net, gro: Set inner transport header offset in tcp/udp GRO hook 2021-08-02 10:20:56 +01:00
udp_tunnel_core.c udp_tunnel: reshuffle NETIF_F_RX_UDP_TUNNEL_PORT checks 2021-01-07 12:53:29 -08:00
udp_tunnel_nic.c udp_tunnel: add the ability to share port tables 2020-09-28 12:50:12 -07:00
udp_tunnel_stub.c udp_tunnel: add central NIC RX port offload infrastructure 2020-07-10 13:54:00 -07:00
udp.c udp: check encap socket in __udp_lib_err 2021-07-21 08:49:31 -07:00
udplite.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
xfrm4_input.c
xfrm4_output.c
xfrm4_policy.c
xfrm4_protocol.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
xfrm4_state.c
xfrm4_tunnel.c xfrm: remove description from xfrm_type struct 2021-06-09 09:38:52 +02:00