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Eric Dumazet 9ba2b4ac35 tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd 
commit 11825765291a93d8e7f44230da67b9f607c777bf upstream.

syzbot got a new report [1] finally pointing to a very old bug,
added in initial support for MTU probing.

tcp_mtu_probe() has checks about starting an MTU probe if
tcp_snd_cwnd(tp) >= 11.

But nothing prevents tcp_snd_cwnd(tp) to be reduced later
and before the MTU probe succeeds.

This bug would lead to potential zero-divides.

Debugging added in commit 40570375356c ("tcp: add accessors
to read/set tp->snd_cwnd") has paid off :)

While we are at it, address potential overflows in this code.

[1]
WARNING: CPU: 1 PID: 14132 at include/net/tcp.h:1219 tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712
Modules linked in:
CPU: 1 PID: 14132 Comm: syz-executor.2 Not tainted 5.18.0-syzkaller-07857-gbabf0bb978e3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:tcp_snd_cwnd_set include/net/tcp.h:1219 [inline]
RIP: 0010:tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712
Code: 74 08 48 89 ef e8 da 80 17 f9 48 8b 45 00 65 48 ff 80 80 03 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 aa b0 c5 f8 <0f> 0b e9 16 fe ff ff 48 8b 4c 24 08 80 e1 07 38 c1 0f 8c c7 fc ff
RSP: 0018:ffffc900079e70f8 EFLAGS: 00010287
RAX: ffffffff88c0f7f6 RBX: ffff8880756e7a80 RCX: 0000000000040000
RDX: ffffc9000c6c4000 RSI: 0000000000031f9e RDI: 0000000000031f9f
RBP: 0000000000000000 R08: ffffffff88c0f606 R09: ffffc900079e7520
R10: ffffed101011226d R11: 1ffff1101011226c R12: 1ffff1100eadcf50
R13: ffff8880756e72c0 R14: 1ffff1100eadcf89 R15: dffffc0000000000
FS:  00007f643236e700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1ab3f1e2a0 CR3: 0000000064fe7000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 tcp_clean_rtx_queue+0x223a/0x2da0 net/ipv4/tcp_input.c:3356
 tcp_ack+0x1962/0x3c90 net/ipv4/tcp_input.c:3861
 tcp_rcv_established+0x7c8/0x1ac0 net/ipv4/tcp_input.c:5973
 tcp_v6_do_rcv+0x57b/0x1210 net/ipv6/tcp_ipv6.c:1476
 sk_backlog_rcv include/net/sock.h:1061 [inline]
 __release_sock+0x1d8/0x4c0 net/core/sock.c:2849
 release_sock+0x5d/0x1c0 net/core/sock.c:3404
 sk_stream_wait_memory+0x700/0xdc0 net/core/stream.c:145
 tcp_sendmsg_locked+0x111d/0x3fc0 net/ipv4/tcp.c:1410
 tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1448
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 __sys_sendto+0x439/0x5c0 net/socket.c:2119
 __do_sys_sendto net/socket.c:2131 [inline]
 __se_sys_sendto net/socket.c:2127 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:2127
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7f6431289109
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f643236e168 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f643139c100 RCX: 00007f6431289109
RDX: 00000000d0d0c2ac RSI: 0000000020000080 RDI: 000000000000000a
RBP: 00007f64312e308d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff372533af R14: 00007f643236e300 R15: 0000000000022000

Fixes: 5d424d5a674f ("[TCP]: MTU probing")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-06-14 18:32:47 +02:00
..
bpfilter
net: Revert "net: optimize the sockptr_t for unified kernel/user address spaces"
2020-08-10 12:06:44 -07:00
netfilter
netfilter: ipt_CLUSTERIP: fix refcount leak in clusterip_tg_check()
2022-01-27 10:54:00 +01:00
af_inet.c
gso: do not skip outer ip header in case of ipip and net_failover
2022-03-02 11:42:49 +01:00
ah4.c
xfrm: Use actual socket sk instead of skb socket for xfrm_output_resume
2021-04-14 08:42:05 +02:00
arp.c
ipv4: Invalidate neighbour for broadcast address upon address addition
2022-04-13 21:00:57 +02:00
bpf_tcp_ca.c
bpf: Change bpf_sk_storage_*() to accept ARG_PTR_TO_BTF_ID_SOCK_COMMON
2020-09-25 13:58:01 -07:00
cipso_ipv4.c
net: ipv4: fix memory leak in netlbl_cipsov4_add_std
2021-06-23 14:42:41 +02:00
datagram.c
inet: stop leaking jiffies on the wire
2019-11-01 14:57:52 -07:00
devinet.c
net: return correct error code
2021-12-08 09:03:18 +01:00
esp4_offload.c
esp: Fix BEET mode inter address family tunneling on GSO
2022-03-16 14:15:57 +01:00
esp4.c
esp: limit skb_page_frag_refill use to a single page
2022-04-27 13:53:48 +02:00
fib_frontend.c
ipv4: Invalidate neighbour for broadcast address upon address addition
2022-04-13 21:00:57 +02:00
fib_lookup.h
net: add net available in build_state
2020-03-29 22:30:57 -07:00
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
ipv4: convert fib_num_tclassid_users to atomic_t
2021-12-08 09:03:26 +01:00
fib_semantics.c
net: ipv4: fix route with nexthop object delete warning
2022-04-13 21:01:04 +02:00
fib_trie.c
ipv4: Silence suspicious RCU usage warning
2020-08-26 15:58:48 -07:00
fou.c
genetlink: move to smaller ops wherever possible
2020-10-02 19:11:11 -07:00
gre_demux.c
erspan: fix version 1 check in gre_parse_header()
2021-01-12 20:18:12 +01:00
gre_offload.c
net: gre: recompute gre csum for sctp over gre tunnels
2020-08-03 15:29:44 -07:00
icmp.c
lsm,selinux: pass flowi_common instead of flowi to the LSM hooks
2022-06-09 10:21:09 +02:00
igmp.c
net: igmp: respect RCU rules in ip_mc_source() and ip_mc_msfilter()
2022-05-12 12:25:43 +02:00
inet_connection_sock.c
lsm,selinux: pass flowi_common instead of flowi to the LSM hooks
2022-06-09 10:21:09 +02:00
inet_diag.c
inet_diag: fix kernel-infoleak for UDP sockets
2021-12-22 09:30:53 +01:00
inet_fragment.c
inet: frags: annotate races around fqdir->dead and fqdir->high_thresh
2022-01-27 10:54:33 +01:00
inet_hashtables.c
secure_seq: use the 64 bits of the siphash for port offset calculation
2022-05-30 09:33:23 +02:00
inet_timewait_sock.c
…
inetpeer.c
inetpeer: fix data-race in inet_putpeer / inet_putpeer
2019-11-07 16:15:56 -08:00
ip_forward.c
…
ip_fragment.c
inet: frags: annotate races around fqdir->dead and fqdir->high_thresh
2022-01-27 10:54:33 +01:00
ip_gre.c
ip_gre: test csum_start instead of transport header
2022-06-14 18:32:41 +02:00
ip_input.c
bpf: Add socket assign support
2020-03-30 13:45:04 -07:00
ip_options.c
net: clean up codestyle for net/ipv4
2020-08-25 06:28:02 -07:00
ip_output.c
lsm,selinux: pass flowi_common instead of flowi to the LSM hooks
2022-06-09 10:21:09 +02:00
ip_sockglue.c
net: Remove duplicated midx check against 0
2020-08-25 06:23:59 -07:00
ip_tunnel_core.c
tunnels: Fix off-by-one in lower MTU bounds for ICMP/ICMPv6 replies
2020-11-09 15:39:39 -08:00
ip_tunnel.c
net: Set true network header for ECN decapsulation
2021-08-04 12:46:42 +02:00
ip_vti.c
net: always use icmp{,v6}_ndo_send from ndo_start_xmit
2021-03-17 17:06:12 +01:00
ipcomp.c
ipcomp: assign if_id to child tunnel from parent tunnel
2020-07-09 12:55:37 +02:00
ipconfig.c
net: ipconfig: Don't override command-line hostnames or domains
2021-06-18 10:00:05 +02:00
ipip.c
net: ipip: implement header_ops->parse_protocol for AF_PACKET
2020-06-30 12:29:39 -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
ipmr,ip6mr: acquire RTNL before calling ip[6]mr_free_table() on failure path
2022-02-16 12:54:25 +01:00
Kconfig
net: ipv4: remove duplicate "the the" phrase in Kconfig text
2020-08-18 16:02:16 -07:00
Makefile
udp_tunnel: add central NIC RX port offload infrastructure
2020-07-10 13:54:00 -07:00
metrics.c
…
netfilter.c
netfilter: use actual socket sk rather than skb sk when routing harder
2020-10-30 12:57:39 +01:00
netlink.c
…
nexthop.c
net: nexthop: release IPv6 per-cpu dsts when replacing a nexthop group
2021-12-01 09:19:05 +01:00
ping.c
lsm,selinux: pass flowi_common instead of flowi to the LSM hooks
2022-06-09 10:21:09 +02:00
proc.c
tcp: switch orphan_count to bare per-cpu counters
2021-11-18 14:04:08 +01:00
protocol.c
…
raw_diag.c
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
2020-03-12 22:34:48 -07:00
raw.c
lsm,selinux: pass flowi_common instead of flowi to the LSM hooks
2022-06-09 10:21:09 +02:00
route.c
xfrm: fix "disable_policy" flag use when arriving from different devices
2022-05-25 09:17:58 +02:00
syncookies.c
lsm,selinux: pass flowi_common instead of flowi to the LSM hooks
2022-06-09 10:21:09 +02:00
sysctl_net_ipv4.c
net: Make tcp_allowed_congestion_control readonly in non-init netns
2021-04-21 13:00:57 +02:00
tcp_bbr.c
tcp_bbr: fix u32 wrap bug in round logic if bbr_init() called after 2B packets
2021-08-18 08:59:13 +02:00
tcp_bic.c
tcp: fix stretch ACK bugs in BIC
2020-03-16 18:26:54 -07:00
tcp_bpf.c
bpf, sockmap: Fix double uncharge the mem of sk_msg
2022-04-08 14:40:21 +02:00
tcp_cdg.c
…
tcp_cong.c
net: Only allow init netns to set default tcp cong to a restricted algo
2021-05-14 09:50:46 +02:00
tcp_cubic.c
tcp_cubic: fix spurious Hystart ACK train detections for not-cwnd-limited flows
2021-12-01 09:19:06 +01:00
tcp_dctcp.c
…
tcp_dctcp.h
…
tcp_diag.c
inet_diag: Move the INET_DIAG_REQ_BYTECODE nlattr to cb->data
2020-02-27 18:50:19 -08:00
tcp_fastopen.c
tcp: enable data-less, empty-cookie SYN with TFO_SERVER_COOKIE_NOT_REQD
2021-09-18 13:40:29 +02:00
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: fix tcp_mtup_probe_success vs wrong snd_cwnd
2022-06-14 18:32:47 +02:00
tcp_ipv4.c
tcp: md5: Fix overlap between vrf and non-vrf keys
2021-10-27 09:56:48 +02:00
tcp_lp.c
…
tcp_metrics.c
genetlink: move to smaller ops wherever possible
2020-10-02 19:11:11 -07:00
tcp_minisocks.c
tcp: md5: incorrect tcp_header_len for incoming connections
2022-05-09 09:05:03 +02:00
tcp_nv.c
…
tcp_offload.c
net, gro: Set inner transport header offset in tcp/udp GRO hook
2021-08-12 13:22:05 +02:00
tcp_output.c
tcp: tcp_rtx_synack() can be called from process context
2022-06-14 18:32:36 +02:00
tcp_rate.c
tcp: ensure to use the most recently sent skb when filling the rate sample
2022-05-09 09:05:03 +02:00
tcp_recovery.c
tcp: fix TLP timer not set when CA_STATE changes from DISORDER to OPEN
2021-02-03 23:28:52 +01:00
tcp_scalable.c
net: ipv4: delete repeated words
2020-08-24 17:31:20 -07:00
tcp_timer.c
tcp: make TCP_USER_TIMEOUT accurate for zero window probes
2021-02-03 23:28:51 +01:00
tcp_ulp.c
bpf: sockmap: Only check ULP for TCP sockets
2020-03-09 22:34:58 +01:00
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: fix stretch ACK bugs in Yeah
2020-03-16 18:26:55 -07:00
tcp.c
tcp: make tcp_read_sock() more robust
2022-03-19 13:44:46 +01:00
tunnel4.c
tunnel4: add cb_handler to struct xfrm_tunnel
2020-07-09 12:51:36 +02:00
udp_bpf.c
bpf, sockmap, udp: sk_prot needs inuse_idx set for proc stats
2021-07-28 14:35:37 +02:00
udp_diag.c
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
2020-03-12 22:34:48 -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
2021-08-12 13:22:05 +02:00
udp_tunnel_core.c
udp_tunnel: add central NIC RX port offload infrastructure
2020-07-10 13:54:00 -07:00
udp_tunnel_nic.c
udp_tunnel: Fix end of loop test in udp_tunnel_nic_unregister()
2022-03-02 11:42:51 +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
lsm,selinux: pass flowi_common instead of flowi to the LSM hooks
2022-06-09 10:21:09 +02:00
udplite.c
net/ipv4: remove compat_ip_{get,set}sockopt
2020-07-19 18:16:41 -07:00
xfrm4_input.c
xfrm: state: remove extract_input indirection from xfrm_state_afinfo
2020-05-06 09:40:08 +02:00
xfrm4_output.c
xfrm: fix unused variable warning if CONFIG_NETFILTER=n
2020-05-11 15:12:27 +02:00
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
net: xfrm: unexport __init-annotated xfrm4_protocol_init()
2022-06-14 18:32:40 +02:00
xfrm4_state.c
xfrm: remove output_finish indirection from xfrm_state_afinfo
2020-05-06 09:40:08 +02:00
xfrm4_tunnel.c
xfrm: interface: fix the priorities for ipip and ipv6 tunnels
2020-10-09 12:29:48 +02:00