linux/net
Eric Dumazet 1182576529 tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd
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 4057037535 ("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: 5d424d5a67 ("[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>
2022-05-28 12:42:08 +01:00
..
6lowpan net: don't include ndisc.h from ipv6.h 2022-02-04 14:15:11 -08:00
9p xen/grant-table: remove readonly parameter from functions 2022-03-15 20:34:40 -05:00
802
8021q net: add netif_inherit_tso_max() 2022-05-06 12:07:56 +01:00
appletalk net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
atm net: SO_RCVMARK socket option for SO_MARK with recvmsg() 2022-04-28 13:08:15 -07:00
ax25 ax25: merge repeat codes in ax25_dev_device_down() 2022-05-17 12:24:16 +02:00
batman-adv net: wrap the wireless pointers in struct net_device in an ifdef 2022-05-22 21:51:54 +01:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-23 21:19:17 -07:00
bpf Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2022-05-23 16:07:14 -07:00
bpfilter uaccess: remove CONFIG_SET_FS 2022-02-25 09:36:06 +01:00
bridge Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-19 11:23:59 -07:00
caif net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
can can: isotp: isotp_bind(): do not validate unused address information 2022-05-19 22:11:28 +02:00
ceph libceph: fix misleading ceph_osdc_cancel_request() comment 2022-05-18 21:21:29 +02:00
core net, neigh: Set lower cap for neigh_managed_work rearming 2022-05-25 22:00:48 -07:00
dcb net: dcb: disable softirqs in dcbnl_flush_dev() 2022-03-03 08:01:55 -08:00
dccp net: Add a second bind table hashed by port and address 2022-05-20 18:16:24 -07:00
decnet dn_route: set rt neigh to blackhole_netdev instead of loopback_dev in ifdown 2022-05-17 18:03:23 -07:00
dns_resolver
dsa net: dsa: OF-ware slave_mii_bus 2022-05-23 12:27:53 +01:00
ethernet net: ethernet: set default assignment identifier to NET_NAME_ENUM 2022-04-07 21:04:03 -07:00
ethtool ethtool: Add 10base-T1L link mode entry 2022-05-01 17:45:35 +01:00
hsr net: add per-cpu storage and net->core_stats 2022-03-11 23:17:24 -08:00
ieee802154 net: SO_RCVMARK socket option for SO_MARK with recvmsg() 2022-04-28 13:08:15 -07:00
ife
ipv4 tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd 2022-05-28 12:42:08 +01:00
ipv6 Networking changes for 5.19. 2022-05-25 12:22:58 -07:00
iucv net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
kcm
key Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-19 11:23:59 -07:00
l2tp l2tp: use add READ_ONCE() to fetch sk->sk_bound_dev_if 2022-05-16 10:31:06 +01:00
l3mdev l3mdev: l3mdev_master_upper_ifindex_by_index_rcu should be using netdev_master_upper_dev_get_rcu 2022-04-15 14:27:24 -07:00
lapb
llc llc: only change llc->dev when bind() succeeds 2022-03-25 16:55:41 -07:00
mac80211 wireless-next patches for v5.19 2022-05-19 13:01:08 -07:00
mac802154 net: mac802154: Fix symbol durations 2022-04-30 20:29:47 +02:00
mctp Networking changes for 5.19. 2022-05-25 12:22:58 -07:00
mpls net: mpls: fix memdup.cocci warning 2022-04-07 21:06:41 -07:00
mptcp Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2022-05-23 16:07:14 -07:00
ncsi
netfilter netfilter: nf_tables: set element extended ACK reporting support 2022-05-27 11:16:38 +02:00
netlabel netlabel: fix out-of-bounds memory accesses 2022-03-21 10:59:11 +00:00
netlink Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-12 16:15:30 -07:00
netrom net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
nfc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-19 11:23:59 -07:00
nsh
openvswitch openvswitch: fix OOB access in reserve_sfa_size() 2022-04-15 11:50:02 +01:00
packet net: SO_RCVMARK socket option for SO_MARK with recvmsg() 2022-04-28 13:08:15 -07:00
phonet net: remove noblock parameter from recvmsg() entities 2022-04-12 15:00:25 +02:00
psample
qrtr net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
rds net: rds: use maybe_get_net() when acquiring refcount on TCP sockets 2022-05-05 16:44:49 -07:00
rfkill rfkill: make new event layout opt-in 2022-03-18 13:09:17 +02:00
rose ROSE: Remove unused code and clean up some inconsistent indenting 2022-05-09 17:19:27 -07:00
rxrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-23 21:19:17 -07:00
sched Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-19 11:23:59 -07:00
sctp stcp: Use memset_after() to zero sctp_stream_out_ext 2022-05-20 17:42:53 -07:00
smc net/smc: fixes for converting from "struct smc_cdc_tx_pend **" to "struct smc_wr_tx_pend_priv *" 2022-05-28 12:36:26 +01:00
strparser
sunrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-19 11:23:59 -07:00
switchdev net: switchdev: remove lag_mod_cb from switchdev_handle_fdb_event_to_device 2022-02-24 21:31:43 -08:00
tipc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-03-23 10:53:49 -07:00
tls net: tls: fix messing up lists when bpf enabled 2022-05-19 17:55:06 -07:00
unix Networking changes for 5.19. 2022-05-25 12:22:58 -07:00
vmw_vsock vsock/virtio: add support for device suspend/resume 2022-05-02 16:04:34 -07:00
wireless wireless-next patches for v5.19 2022-05-19 13:01:08 -07:00
x25 x25: remove redundant pointer dev 2022-05-10 11:59:22 +02:00
xdp Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-04-28 13:02:01 -07:00
xfrm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-19 11:23:59 -07:00
compat.c
devres.c
Kconfig page_pool: Add allocation stats 2022-03-03 09:55:28 +00:00
Kconfig.debug net: add CONFIG_DEBUG_NET 2022-05-11 12:43:10 +01:00
Makefile
socket.c Networking changes for 5.19. 2022-05-25 12:22:58 -07:00
sysctl_net.c