BUG: "hc->tx_t_ipi == NUM" holds (exception!) at net/dccp/ccids/ccid3.c:LINE/ccid3_update_send

BUG: "hc->tx_t_ipi == NUM" holds (exception!) at net/dccp/ccids/ccid3.c:LINE/ccid3_update_send_interval()
Status: upstream: reported C repro on 2022/01/10 16:16
Reported-by: syzbot+94641ba6c1d768b1e35e@syzkaller.appspotmail.com
First crash: 15d, last: 18h07m

Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: BUG: "hc->tx_t_ipi == NUM" holds (exception!) at net/dccp/ccids/ccid3.c:LINE/ccid3_update_send_interval() (log)
Repro: C syz .config

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.19	BUG: "hc->tx_t_ipi == NUM" holds (exception!) at net/dccp/ccids/ccid3.c:LINE/ccid3_update_send_interval()	C			2	2d07h	2d08h	0/1	upstream: reported C repro on 2022/01/22 17:14

Sample crash report:

BUG: "hc->tx_t_ipi == 0" holds (exception!) at net/dccp/ccids/ccid3.c:90/ccid3_update_send_interval()
CPU: 1 PID: 3774 Comm: syz-executor037 Not tainted 5.17.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 ccid3_update_send_interval net/dccp/ccids/ccid3.c:90 [inline]
 ccid3_update_send_interval.cold+0x87/0x93 net/dccp/ccids/ccid3.c:86
 ccid3_hc_tx_update_s net/dccp/ccids/ccid3.c:169 [inline]
 ccid3_hc_tx_packet_sent+0x12e/0x160 net/dccp/ccids/ccid3.c:353
 ccid_hc_tx_packet_sent net/dccp/ccid.h:175 [inline]
 dccp_xmit_packet+0x2f2/0x750 net/dccp/output.c:289
 dccp_write_xmit+0x16d/0x1d0 net/dccp/output.c:366
 dccp_sendmsg+0x924/0xca0 net/dccp/proto.c:783
 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:819
 sock_sendmsg_nosec net/socket.c:705 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:725
 ____sys_sendmsg+0x331/0x810 net/socket.c:2413
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2467
 __sys_sendmmsg+0x195/0x470 net/socket.c:2553
 __do_sys_sendmmsg net/socket.c:2582 [inline]
 __se_sys_sendmmsg net/socket.c:2579 [inline]
 __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2579
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f4759b8fe49
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 18 00 00 90 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:00007f4759b152f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000022 RCX: 00007f4759b8fe49
RDX: 0000000000000001 RSI: 0000000020000fc0 RDI: 0000000000000004
RBP: 00007f4759c114b8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4759c114b0
R13: 00007f4759c114bc R14: 00007f4759bde6f4 R15: e7594119f9b8c840
 </TASK>

Crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci-upstream-kasan-gce	2022/01/24 07:32	upstream	dd81e1c7d5fb	214351e1	.config	log	report	syz	C		BUG: "hc->tx_t_ipi == NUM" holds (exception!) at net/dccp/ccids/ccid3.c:LINE/ccid3_update_send_interval()
ci-upstream-net-kasan-gce	2022/01/09 11:15	net-next	82192cb497f9	2ca0d385	.config	log	report	syz	C		BUG: "hc->tx_t_ipi == NUM" holds (exception!) at net/dccp/ccids/ccid3.c:LINE/ccid3_update_send_interval()
ci-upstream-kasan-gce-selinux-root	2022/01/17 09:41	upstream	79e06c4c4950	723cfaf0	.config	log	report			info	BUG: "hc->tx_t_ipi == NUM" holds (exception!) at net/dccp/ccids/ccid3.c:LINE/ccid3_update_send_interval()
ci-upstream-kasan-gce-386	2022/01/15 09:17	upstream	112450df61b7	723cfaf0	.config	log	report			info	BUG: "hc->tx_t_ipi == NUM" holds (exception!) at net/dccp/ccids/ccid3.c:LINE/ccid3_update_send_interval()
ci-upstream-net-this-kasan-gce	2022/01/12 08:05	net	29b3881b7977	44d1319a	.config	log	report			info	BUG: "hc->tx_t_ipi == NUM" holds (exception!) at net/dccp/ccids/ccid3.c:LINE/ccid3_update_send_interval()
ci-upstream-net-kasan-gce	2022/01/09 05:57	net-next	82192cb497f9	2ca0d385	.config	log	report			info	BUG: "hc->tx_t_ipi == NUM" holds (exception!) at net/dccp/ccids/ccid3.c:LINE/ccid3_update_send_interval()