syzbot


WARNING in __skb_flow_dissect

Status: upstream: reported C repro on 2026/01/17 07:47
Reported-by: syzbot+84112fa28f0a5cc0669f@syzkaller.appspotmail.com
First crash: 127d, last: 13d
Bug presence (1)
Date Name Commit Repro Result
2026/04/21 upstream (ToT) e2683c8868d0 C Failed due to an error; will retry later
Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in __skb_flow_dissect (6) net -1 1 747d 747d 27/29 fixed on 2024/08/14 19:57
upstream WARNING in __skb_flow_dissect net -1 syz 3 2782d 2783d 11/29 fixed on 2018/10/11 18:37
upstream WARNING in __skb_flow_dissect (5) net -1 1 787d 787d 0/29 closed as invalid on 2024/04/26 11:59
upstream WARNING in __skb_flow_dissect (7) net -1 275 131d 124d 29/29 fixed on 2026/05/06 16:40
linux-6.6 WARNING in __skb_flow_dissect origin:lts-only -1 C 12 3d07h 41d 0/2 upstream: reported C repro on 2026/04/13 06:50
upstream WARNING in __skb_flow_dissect (3) net -1 syz 224 2686d 2775d 11/29 fixed on 2019/03/06 07:43
upstream WARNING in __skb_flow_dissect (4) net -1 C error 6 1296d 1305d 22/29 fixed on 2023/02/24 13:50

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 4513 at net/core/flow_dissector.c:1027 __skb_flow_dissect+0x95c/0x5988 net/core/flow_dissector.c:1022
Modules linked in:
CPU: 0 PID: 4513 Comm: kworker/0:12 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: rcu_gp process_srcu
pstate: 42400005 (nZcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : __skb_flow_dissect+0x95c/0x5988 net/core/flow_dissector.c:1022
lr : __skb_flow_dissect+0x95c/0x5988 net/core/flow_dissector.c:1022
sp : ffff800008006740
x29: ffff800008006d90 x28: ffff800008006ea0 x27: 0000000000000002
x26: ffff0000c3f29270 x25: ffff8000152251dc x24: dfff800000000000
x23: 0000000000000000 x22: 1ffff00002a44a3c x21: 1ffff00002a44a3c
x20: ffff8000152251e2 x19: ffff700001000d2c x18: ffff800011b9bf60
x17: 00000000ffff0000 x16: ffff8000082d92bc x15: 0000000000000000
x14: 000000000000000a x13: 1ffff00002a44071 x12: 0000000000ff0100
x11: ff0080000fdb0e48 x10: 0000000000000000 x9 : ffff80000fdb0e48
x8 : ffff0000d6e7d340 x7 : ffff80000fdb7d28 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000002
x2 : 0000000000000008 x1 : ffff80001208bc80 x0 : 0000000000000001
Call trace:
 __skb_flow_dissect+0x95c/0x5988 net/core/flow_dissector.c:1022
 skb_flow_dissect_flow_keys include/linux/skbuff.h:1531 [inline]
 ___skb_get_hash+0x7c/0x5b8 net/core/flow_dissector.c:1708
 __skb_get_hash+0xb8/0x228 net/core/flow_dissector.c:1773
 skb_get_hash include/linux/skbuff.h:1573 [inline]
 nft_trace_init+0x188/0x358 net/netfilter/nf_tables_trace.c:292
 nft_do_chain+0x1260/0x12e8 net/netfilter/nf_tables_core.c:243
 nf_route_table_hook6+0x218/0x5ec net/netfilter/nft_chain_route.c:88
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_slow+0xb4/0x1f4 net/netfilter/core.c:614
 nf_hook include/linux/netfilter.h:257 [inline]
 __ip6_local_out+0x6b0/0x7cc net/ipv6/output_core.c:149
 ip6_local_out+0x3c/0x15c net/ipv6/output_core.c:159
 ip6tunnel_xmit include/net/ip6_tunnel.h:161 [inline]
 udp_tunnel6_xmit_skb+0x434/0x8f0 net/ipv6/ip6_udp_tunnel.c:109
 tipc_udp_xmit+0x484/0x9b8 net/tipc/udp_media.c:220
 tipc_udp_send_msg+0x254/0x380 net/tipc/udp_media.c:258
 tipc_bearer_xmit_skb+0x240/0x380 net/tipc/bearer.c:577
 tipc_disc_timeout+0x4d8/0x628 net/tipc/discover.c:338
 call_timer_fn+0x1b8/0x95c kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x478/0x6f0 kernel/time/timer.c:2023
 run_timer_softirq+0x7c/0x114 kernel/time/timer.c:2036
 handle_softirqs+0x318/0xc60 kernel/softirq.c:596
 __do_softirq+0x14/0x20 kernel/softirq.c:630
 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80
 call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:897
 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:85
 invoke_softirq kernel/softirq.c:477 [inline]
 __irq_exit_rcu+0x23c/0x438 kernel/softirq.c:679
 irq_exit_rcu+0x14/0x84 kernel/softirq.c:691
 __el1_irq arch/arm64/kernel/entry-common.c:472 [inline]
 el1_interrupt+0x38/0x54 arch/arm64/kernel/entry-common.c:486
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491
 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581
 __arch_counter_get_cntvct_stable arch/arm64/include/asm/arch_timer.h:202 [inline]
 __delay_cycles+0x15c/0x21c arch/arm64/lib/delay.c:38
 __delay+0x144/0x1c4 arch/arm64/lib/delay.c:63
 __const_udelay arch/arm64/lib/delay.c:70 [inline]
 __udelay+0x60/0x70 arch/arm64/lib/delay.c:76
 try_check_zero+0x388/0x3b8 kernel/rcu/srcutree.c:975
 srcu_advance_state kernel/rcu/srcutree.c:1549 [inline]
 process_srcu+0x16c/0xffc kernel/rcu/srcutree.c:1651
 process_one_work+0x7f8/0x13a4 kernel/workqueue.c:2292
 worker_thread+0x8c4/0xfec kernel/workqueue.c:2439
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850
irq event stamp: 10229
hardirqs last  enabled at (10228): [<ffff8000081ab57c>] __local_bh_enable_ip+0x1f8/0x37c kernel/softirq.c:426
hardirqs last disabled at (10229): [<ffff800011a389f4>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last  enabled at (9714): [<ffff80000fdd2608>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (10207): [<ffff800008020164>] __do_softirq+0x14/0x20 kernel/softirq.c:630
---[ end trace 0000000000000000 ]---

Crashes (22):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/10 17:55 linux-6.1.y 128a674368bf 29233ece .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/24 09:03 linux-6.1.y cd9b81672742 4f25b9b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/03/28 10:26 linux-6.1.y 1989cd3d56e2 356bdfc9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in __skb_flow_dissect
2026/03/20 05:38 linux-6.1.y f2ddafa93a25 2f245add .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in __skb_flow_dissect
2026/05/10 15:32 linux-6.1.y 128a674368bf 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/04/18 21:28 linux-6.1.y 7c87defbd336 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/04/17 03:30 linux-6.1.y 8e8fc038cad5 de0a551d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/04/13 09:52 linux-6.1.y 8e8fc038cad5 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/04/13 06:31 linux-6.1.y 8e8fc038cad5 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/04/08 03:43 linux-6.1.y 1989cd3d56e2 2c961e87 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/03/19 15:49 linux-6.1.y f2ddafa93a25 bd6dcb30 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/02/25 03:15 linux-6.1.y 779f9571ac3e 787dfb7c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/26 15:12 linux-6.1.y cd9b81672742 a4c52dd6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/26 02:08 linux-6.1.y cd9b81672742 55756628 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/24 15:19 linux-6.1.y cd9b81672742 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/24 15:19 linux-6.1.y cd9b81672742 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/24 03:02 linux-6.1.y cd9b81672742 4f25b9b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/21 10:54 linux-6.1.y cd9b81672742 6f1aa2f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/20 17:52 linux-6.1.y cd9b81672742 06648d9c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/20 06:01 linux-6.1.y cd9b81672742 572effc1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/17 07:48 linux-6.1.y bec0e10ee67e 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
2026/01/17 07:47 linux-6.1.y bec0e10ee67e 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in __skb_flow_dissect
* Struck through repros no longer work on HEAD.