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cf12e6f912
linux/net/ipv4
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Jon Maxwell cf12e6f912 tcp: don't free a FIN sk_buff in tcp_remove_empty_skb() 
v1: Implement a more general statement as recommended by Eric Dumazet. The
sequence number will be advanced, so this check will fix the FIN case and
other cases.

A customer reported sockets stuck in the CLOSING state. A Vmcore revealed that
the write_queue was not empty as determined by tcp_write_queue_empty() but the
sk_buff containing the FIN flag had been freed and the socket was zombied in
that state. Corresponding pcaps show no FIN from the Linux kernel on the wire.

Some instrumentation was added to the kernel and it was found that there is a
timing window where tcp_sendmsg() can run after tcp_send_fin().

tcp_sendmsg() will hit an error, for example:

1269 ▹       if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))↩
1270 ▹       ▹       goto do_error;↩

tcp_remove_empty_skb() will then free the FIN sk_buff as "skb->len == 0". The
TCP socket is now wedged in the FIN-WAIT-1 state because the FIN is never sent.

If the other side sends a FIN packet the socket will transition to CLOSING and
remain that way until the system is rebooted.

Fix this by checking for the FIN flag in the sk_buff and don't free it if that
is the case. Testing confirmed that fixed the issue.

Fixes: fdfc5c8594 ("tcp: remove empty skb from write queue in error cases")
Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com>
Reported-by: Monir Zouaoui <Monir.Zouaoui@mail.schwarz>
Reported-by: Simon Stier <simon.stier@mail.schwarz>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-10-26 13:10:04 +01:00
..
bpfilter net: Revert "net: optimize the sockptr_t for unified kernel/user address spaces" 2020-08-10 12:06:44 -07:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next 2021-10-18 14:05:25 +01:00
af_inet.c net: snmp: inline snmp_get_cpu_field() 2021-09-30 14:17:10 +01:00
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: tcp: Allow bpf-tcp-cc to call bpf_(get|set)sockopt 2021-08-25 17:40:35 -07:00
cipso_ipv4.c NET: IPV4: fix error "do not initialise globals to 0" 2021-09-19 12:43:56 +01:00
datagram.c net/ipv4/datagram.c: remove superfluous header files from datagram.c 2021-09-29 11:39:33 +01:00
devinet.c net: add extack arg for link ops 2021-08-04 10:01:26 +01:00
esp4_offload.c xfrm: remove description from xfrm_type struct 2021-06-09 09:38:52 +02:00
esp4.c ipsec: Remove unneeded extra variable in esp4 esp_ssg_unref() 2021-07-20 16:14:23 +02:00
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 net: ipv4: remove superfluous header files from fib_notifier.c 2021-09-28 17:32:56 -07:00
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 net: ipv4: Fix rtnexthop len when RTA_FLOW is present 2021-09-24 14:07:10 +01:00
fib_trie.c memcg: enable accounting for IP address and routing-related objects 2021-07-20 06:00:38 -07:00
fou.c fou: remove sparse errors 2021-08-31 12:03:33 +01:00
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 icmp: fix icmp_ext_echo_iio parsing in icmp_build_probe 2021-10-14 07:54:47 -07:00
igmp.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-08-13 06:41:22 -07:00
inet_connection_sock.c tcp: switch orphan_count to bare per-cpu counters 2021-10-15 11:28:34 +01:00
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: switch orphan_count to bare per-cpu counters 2021-10-15 11:28:34 +01:00
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 ip: use dev_addr_set() in tunnels 2021-10-13 09:41:37 -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: ipv4: Fix the warning for dereference 2021-08-30 12:47:09 +01:00
ip_sockglue.c ipv4: guard IP_MINTTL with a static key 2021-10-25 18:02:14 -07:00
ip_tunnel_core.c net: ip_tunnel: clean up endianness conversions 2021-01-08 19:25:35 -08:00
ip_tunnel.c ip: use dev_addr_set() in tunnels 2021-10-13 09:41:37 -07:00
ip_vti.c ip: use dev_addr_set() in tunnels 2021-10-13 09:41:37 -07:00
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 ip: use dev_addr_set() in tunnels 2021-10-13 09:41:37 -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: Fix memory leaks in nexthop notification chain listeners 2021-09-23 12:33:22 +01:00
ping.c Revert "Revert "ipv4: fix memory leaks in ip_cmsg_send() callers"" 2021-09-14 14:24:31 +01:00
proc.c tcp: switch orphan_count to bare per-cpu counters 2021-10-15 11:28:34 +01:00
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 Revert "Revert "ipv4: fix memory leaks in ip_cmsg_send() callers"" 2021-09-14 14:24:31 +01:00
route.c net/ipv4/route.c: remove superfluous header files from route.c 2021-09-20 13:09:06 +01:00
syncookies.c net/ipv4/syncookies.c: remove superfluous header files from syncookies.c 2021-09-21 10:48:47 +01:00
sysctl_net_ipv4.c tcp: remove sk_{tr}x_skb_cache 2021-09-23 12:50:26 +01:00
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 net/ipv4/tcp_fastopen.c: remove superfluous header files from tcp_fastopen.c 2021-09-20 13:09:06 +01:00
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 tcp: adjust rcv_ssthresh according to sk_reserved_mem 2021-09-30 13:36:46 +01:00
tcp_ipv4.c ipv4: guard IP_MINTTL with a static key 2021-10-25 18:02:14 -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 net/ipv4/tcp_minisocks.c: remove superfluous header files from tcp_minisocks.c 2021-09-20 13:09:06 +01:00
tcp_nv.c net/ipv4/tcp_nv.c: remove superfluous header files from tcp_nv.c 2021-09-27 12:47:39 +01:00
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 tcp: adjust rcv_ssthresh according to sk_reserved_mem 2021-09-30 13:36:46 +01:00
tcp_rate.c tcp: tracking packets with CE marks in BW rate sample 2021-09-24 14:16:40 +01:00
tcp_recovery.c tcp: more accurately check DSACKs to grow RACK reordering window 2021-07-27 20:07:21 +01:00
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: don't free a FIN sk_buff in tcp_remove_empty_skb() 2021-10-26 13:10:04 +01:00
tunnel4.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
udp_bpf.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-07-23 16:13:06 +01:00
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 fou: remove sparse errors 2021-08-31 12:03:33 +01:00
udp_tunnel_core.c net/ipv4/udp_tunnel_core.c: remove superfluous header files from udp_tunnel_core.c 2021-09-21 10:17:20 +01:00
udp_tunnel_nic.c udp_tunnel: Fix udp_tunnel_nic work-queue type 2021-09-13 12:38:45 +01:00
udp_tunnel_stub.c udp_tunnel: add central NIC RX port offload infrastructure 2020-07-10 13:54:00 -07:00
udp.c net: prefer socket bound to interface when not in VRF 2021-10-07 07:27:55 -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