syzbot


WARNING in subflow_data_ready

Status: upstream: reported C repro on 2025/12/10 13:17
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+32c1241cc455e5d3fc88@syzkaller.appspotmail.com
First crash: 7d06h, last: 4d13h
Bug presence (1)
Date Name Commit Repro Result
2025/12/11 upstream (ToT) d358e5254674 C [report] WARNING in subflow_data_ready
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in subflow_data_ready mptcp -1 42 699d 784d 25/29 fixed on 2024/01/20 21:18
upstream WARNING in subflow_data_ready (3) mptcp -1 1 200d 200d 0/29 closed as invalid on 2025/06/27 12:28
linux-6.1 WARNING in subflow_data_ready origin:lts-only -1 C unreliable 6 561d 706d 0/3 upstream: reported C repro on 2024/01/11 08:07
upstream WARNING in subflow_data_ready (2) mptcp -1 C done 9 675d 693d 0/29 auto-obsoleted due to no activity on 2024/05/21 09:30
upstream WARNING in subflow_data_ready (4) mptcp -1 C 331 2h06m 119d 0/29 upstream: reported C repro on 2025/08/20 12:41

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1143 at net/mptcp/subflow.c:1472 subflow_data_ready+0x412/0x660 net/mptcp/subflow.c:1471
Modules linked in:
CPU: 0 PID: 1143 Comm: kworker/u4:6 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: krdsd rds_send_worker
RIP: 0010:subflow_data_ready+0x412/0x660 net/mptcp/subflow.c:1471
Code: 88 38 f7 0f 0b e9 4e fd ff ff e8 89 88 38 f7 48 89 df 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 83 0d 00 00 e8 6e 88 38 f7 <0f> 0b e9 3f fe ff ff 44 89 f9 80 e1 07 38 c1 0f 8c 36 fc ff ff 4c
RSP: 0018:ffffc90000006758 EFLAGS: 00010246
RAX: ffffffff8a4d0852 RBX: ffff888061a1db00 RCX: ffff888023be8000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff88802b8ebae7 R09: 1ffff1100571d75c
R10: dffffc0000000000 R11: ffffed100571d75d R12: ffff88802b8eb200
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000180 CR3: 000000002ec18000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 tcp_data_queue+0x21b2/0x5a80 net/ipv4/tcp_input.c:5226
 tcp_rcv_state_process+0x2772/0x4130 net/ipv4/tcp_input.c:6858
 tcp_v6_do_rcv+0xc46/0x12d0 net/ipv6/tcp_ipv6.c:1503
 tcp_v6_rcv+0x1fd4/0x26a0 net/ipv6/tcp_ipv6.c:1743
 ip6_protocol_deliver_rcu+0xb7a/0x13c0 net/ipv6/ip6_input.c:438
 ip6_input_finish+0x184/0x2c0 net/ipv6/ip6_input.c:483
 NF_HOOK+0x303/0x390 include/linux/netfilter.h:304
 ip_sabotage_in+0x1f4/0x280 net/bridge/br_netfilter_hooks.c:1001
 nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
 nf_hook_slow+0xbd/0x200 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:259 [inline]
 NF_HOOK+0x204/0x390 include/linux/netfilter.h:302
 __netif_receive_skb_one_core net/core/dev.c:5608 [inline]
 __netif_receive_skb+0xcc/0x290 net/core/dev.c:5722
 netif_receive_skb_internal net/core/dev.c:5808 [inline]
 netif_receive_skb+0x1bc/0x6f0 net/core/dev.c:5867
 NF_HOOK+0x9a/0x380 include/linux/netfilter.h:304
 br_handle_frame_finish+0xf31/0x1950 net/bridge/br_input.c:208
 br_nf_hook_thresh+0x3b6/0x480 net/bridge/br_netfilter_hooks.c:1184
 br_nf_pre_routing_finish_ipv6+0x9e3/0xd90 net/bridge/br_netfilter_ipv6.c:-1
 NF_HOOK include/linux/netfilter.h:304 [inline]
 br_nf_pre_routing_ipv6+0x34d/0x680 net/bridge/br_netfilter_ipv6.c:184
 nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
 br_handle_frame+0x957/0x14c0 net/bridge/br_input.c:424
 __netif_receive_skb_core+0xf6b/0x3ac0 net/core/dev.c:5502
 __netif_receive_skb_one_core net/core/dev.c:5606 [inline]
 __netif_receive_skb+0x74/0x290 net/core/dev.c:5722
 process_backlog+0x380/0x6e0 net/core/dev.c:6050
 __napi_poll+0xc0/0x460 net/core/dev.c:6612
 napi_poll net/core/dev.c:6679 [inline]
 net_rx_action+0x5ea/0xbf0 net/core/dev.c:6815
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 do_softirq+0xed/0x180 kernel/softirq.c:479
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x178/0x1c0 kernel/softirq.c:406
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:856 [inline]
 __dev_queue_xmit+0x1449/0x35a0 net/core/dev.c:4452
 neigh_output include/net/neighbour.h:543 [inline]
 ip6_finish_output2+0xe2e/0x1650 net/ipv6/ip6_output.c:141
 dst_output include/net/dst.h:467 [inline]
 NF_HOOK include/linux/netfilter.h:304 [inline]
 ip6_xmit+0x10aa/0x1840 net/ipv6/ip6_output.c:360
 inet6_csk_xmit+0x472/0x710 net/ipv6/inet6_connection_sock.c:135
 __tcp_transmit_skb+0x1c97/0x32a0 net/ipv4/tcp_output.c:1422
 tcp_transmit_skb net/ipv4/tcp_output.c:1440 [inline]
 tcp_write_xmit+0x174c/0x62e0 net/ipv4/tcp_output.c:2778
 __tcp_push_pending_frames+0x97/0x340 net/ipv4/tcp_output.c:2963
 tcp_push_pending_frames include/net/tcp.h:2012 [inline]
 __tcp_sock_set_cork net/ipv4/tcp.c:3271 [inline]
 tcp_sock_set_cork+0x126/0x1b0 net/ipv4/tcp.c:3278
 rds_send_xmit+0x1dcb/0x2600 net/rds/send.c:421
 rds_send_worker+0x7d/0x2c0 net/rds/threads.c:200
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Crashes (13):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/11 17:28 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/11 15:26 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/11 13:27 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/11 11:25 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/11 09:39 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/11 06:37 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/11 03:08 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/10 23:18 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/10 21:22 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/10 19:33 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/10 16:33 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/13 06:37 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
2025/12/10 13:17 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in subflow_data_ready
* Struck through repros no longer work on HEAD.