syzbot
WARNING in tcf_ct_flow_table_process_conn
Status:
upstream: reported C repro on 2026/09/12 23:39
Subsystems:
net
Labels:
prio:high
[Documentation on labels]
Reported-by: syzbot+6cc37aba98dac721c415@syzkaller.appspotmail.com
Fix commit:
47abe7a5c4eb
net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure
Patched on: [ci-qemu-gce-upstream-auto ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu-native-arm64-kvm ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root]
First crash: 42d, last: 23d
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Last patch testing requests (1)
Sample crash report:
RDX: 000000000000001c RSI: 0000200000000500 RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000500
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
------------[ cut here ]------------
1
WARNING: net/sched/act_ct.c:437 at tcf_ct_flow_table_add net/sched/act_ct.c:437 [inline], CPU#0: syz-executor278/6366
WARNING: net/sched/act_ct.c:437 at tcf_ct_flow_table_process_conn+0x449/0x7c0 net/sched/act_ct.c:513, CPU#0: syz-executor278/6366
Modules linked in:
CPU: 0 UID: 0 PID: 6366 Comm: syz-executor278 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:tcf_ct_flow_table_add net/sched/act_ct.c:437 [inline]
RIP: 0010:tcf_ct_flow_table_process_conn+0x449/0x7c0 net/sched/act_ct.c:513
Code: 85 81 02 00 00 41 0f b7 2f 31 ff 89 ee e8 2f 67 e9 f7 85 ed 0f 84 7c 01 00 00 e8 e2 62 e9 f7 e9 e0 01 00 00 e8 d8 62 e9 f7 90 <0f> 0b 90 e9 b2 01 00 00 e8 ca 62 e9 f7 4d 89 f7 40 84 ed 74 27 e8
RSP: 0018:ffffc900042d6ef8 EFLAGS: 00010293
RAX: ffffffff89de6f88 RBX: ffff888070202000 RCX: ffff888028c90000
RDX: 0000000000000000 RSI: ffffffff8c6da060 RDI: ffffffff8c6da020
RBP: 0000000000000000 R08: 00000000ffffffff R09: 1ffffffff1dd5cfe
R10: dffffc0000000000 R11: fffffbfff1dd5cff R12: dffffc0000000000
R13: 1ffff1100e04041e R14: ffff8880702020c0 R15: 0000000000000001
FS: 000055556fc09400(0000) GS:ffff888124cd1000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe25dff4c8 CR3: 0000000079ba6000 CR4: 00000000003526f0
Call Trace:
<TASK>
tcf_ct_act+0x2a75/0x4050 net/sched/act_ct.c:1123
tc_act include/net/tc_wrapper.h:131 [inline]
tcf_action_exec+0x185/0x8d0 net/sched/act_api.c:1162
tcf_exts_exec include/net/pkt_cls.h:361 [inline]
basic_classify+0x1b2/0x2d0 net/sched/cls_basic.c:54
tc_classify include/net/tc_wrapper.h:198 [inline]
__tcf_classify net/sched/cls_api.c:1779 [inline]
tcf_classify+0x43d/0x1160 net/sched/cls_api.c:1875
tc_run+0x42d/0x750 net/core/dev.c:4463
sch_handle_ingress net/core/dev.c:4538 [inline]
__netif_receive_skb_core+0x1443/0x30c0 net/core/dev.c:6115
__netif_receive_skb_one_core net/core/dev.c:6262 [inline]
__netif_receive_skb net/core/dev.c:6377 [inline]
netif_receive_skb_internal net/core/dev.c:6463 [inline]
netif_receive_skb+0x1fe/0xbf0 net/core/dev.c:6522
tun_rx_batched+0x1de/0x790 drivers/net/tun.c:1571
tun_get_user+0x2be0/0x44d0 drivers/net/tun.c:2045
tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:2091
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x612/0xba0 fs/read_write.c:687
ksys_write+0x150/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6c0bc30879
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 0f 1f 44 00 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffff5b95668 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ffff5b95690 RCX: 00007f6c0bc30879
RDX: 000000000000001c RSI: 0000200000000500 RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000500
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
* Struck through repros no longer work on HEAD.