BUG: stored value of X_recv is zero at net/dccp/ccids/ccid3.c:LINE/ccid3_first_li()

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5f7735196390 ice: Fix perout start time rounding
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=110ed84a300000
kernel config: https://syzkaller.appspot.com/x/.config?x=e3a20bae04b96ccd
dashboard link: https://syzkaller.appspot.com/bug?extid=67366df631c2523213e2
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
CC: [and...@lunn.ch da...@davemloft.net dc...@vger.kernel.org gusta...@kernel.org ku...@kernel.org linm...@huawei.com linux-...@vger.kernel.org net...@vger.kernel.org net...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+67366d...@syzkaller.appspotmail.com

ccid3_first_li: No RTT estimate available, using fallback RTT
ccid3_first_li: X_recv==0
BUG: stored value of X_recv is zero at net/dccp/ccids/ccid3.c:691/ccid3_first_li()
CPU: 1 PID: 11737 Comm: syz-fuzzer Not tainted 5.14.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
ccid3_first_li.cold+0x67/0x17a net/dccp/ccids/ccid3.c:691
tfrc_lh_interval_add+0x640/0x8e0 net/dccp/ccids/lib/loss_interval.c:157
tfrc_rx_handle_loss+0x41b/0x1fa0 net/dccp/ccids/lib/packet_history.c:328
ccid3_hc_rx_packet_recv+0x385/0xe90 net/dccp/ccids/ccid3.c:744
ccid_hc_rx_packet_recv net/dccp/ccid.h:182 [inline]
dccp_deliver_input_to_ccids+0xd9/0x250 net/dccp/input.c:176
dccp_rcv_established net/dccp/input.c:374 [inline]
dccp_rcv_established+0x107/0x160 net/dccp/input.c:364
dccp_v4_do_rcv+0x130/0x190 net/dccp/ipv4.c:667
sk_backlog_rcv include/net/sock.h:1023 [inline]
__sk_receive_skb+0x29d/0x830 net/core/sock.c:527
dccp_v4_rcv+0xea5/0x19d0 net/dccp/ipv4.c:890
ip_protocol_deliver_rcu+0xa7/0xa20 net/ipv4/ip_input.c:204
ip_local_deliver_finish+0x20a/0x370 net/ipv4/ip_input.c:231
NF_HOOK include/linux/netfilter.h:307 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
ip_local_deliver+0x1b3/0x200 net/ipv4/ip_input.c:252
dst_input include/net/dst.h:458 [inline]
ip_rcv_finish+0x1da/0x2f0 net/ipv4/ip_input.c:429
NF_HOOK include/linux/netfilter.h:307 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
ip_rcv+0xaa/0xd0 net/ipv4/ip_input.c:540
__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5498
__netif_receive_skb+0x24/0x1b0 net/core/dev.c:5612
process_backlog+0x2a5/0x6c0 net/core/dev.c:6492
__napi_poll+0xaf/0x440 net/core/dev.c:7047
napi_poll net/core/dev.c:7114 [inline]
net_rx_action+0x801/0xb40 net/core/dev.c:7201
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558
invoke_softirq kernel/softirq.c:432 [inline]
__irq_exit_rcu+0x16e/0x1c0 kernel/softirq.c:636
irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
sysvec_apic_timer_interrupt+0x45/0xc0 arch/x86/kernel/apic/apic.c:1100
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0033:0x43132b
Code: 48 8b 4c 24 40 48 8b 54 24 38 48 8b 5c 24 30 eb 9e 90 48 89 d3 48 c1 ea 03 48 83 e3 07 48 89 ce 48 89 d9 bf 01 00 00 00 d3 e7 <90> 48 03 50 50 0f b6 1a 40 84 df 74 19 48 8b 44 24 58 48 8b 4c 24
RSP: 002b:000000c00ca55f60 EFLAGS: 00000202
RAX: 00007ff3437d4f70 RBX: 0000000000000001 RCX: 0000000000000001
RDX: 0000000000000014 RSI: 000000c013793420 RDI: 0000000000000002
RBP: 000000c00ca55fa8 R08: 000000000000000b R09: ffffffffffffffff
R10: 00007ff343dc41c0 R11: 000000c000020f58 R12: 000000c00181c6f0
R13: 000000c000020f48 R14: 000000000094d49c R15: 0000000000000000
----------------
Code disassembly (best guess):
0: 48 8b 4c 24 40 mov 0x40(%rsp),%rcx
5: 48 8b 54 24 38 mov 0x38(%rsp),%rdx
a: 48 8b 5c 24 30 mov 0x30(%rsp),%rbx
f: eb 9e jmp 0xffffffaf
11: 90 nop
12: 48 89 d3 mov %rdx,%rbx
15: 48 c1 ea 03 shr $0x3,%rdx
19: 48 83 e3 07 and $0x7,%rbx
1d: 48 89 ce mov %rcx,%rsi
20: 48 89 d9 mov %rbx,%rcx
23: bf 01 00 00 00 mov $0x1,%edi
28: d3 e7 shl %cl,%edi
2a: 90 nop <-- trapping instruction
2b: 48 03 50 50 add 0x50(%rax),%rdx
2f: 0f b6 1a movzbl (%rdx),%ebx
32: 40 84 df test %bl,%dil
35: 74 19 je 0x50
37: 48 8b 44 24 58 mov 0x58(%rsp),%rax
3c: 48 rex.W
3d: 8b .byte 0x8b
3e: 4c rex.WR
3f: 24 .byte 0x24


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.