bisecting fixing commit since 0bddd227f3dc55975e2b8dfa7fc6f959b062a2c7 building syzkaller on bc238812ae6d1f5a7e99ff60b5b3089a73f1cfb3 testing commit 0bddd227f3dc55975e2b8dfa7fc6f959b062a2c7 with gcc (GCC) 8.4.1 20210217 kernel signature: bf492e817354b874897b1bd9a996982df10917e6213b1970c606a30cf4fe6d94 run #0: crashed: general protection fault in free_netdev run #1: crashed: KASAN: use-after-free Read in netdevice_event_work_handler run #2: crashed: KASAN: use-after-free Read in netdevice_event_work_handler run #3: crashed: KASAN: use-after-free Read in netdevice_event_work_handler run #4: crashed: general protection fault in free_netdev run #5: crashed: KASAN: use-after-free Read in netdevice_event_work_handler run #6: crashed: KASAN: use-after-free Read in netdevice_event_work_handler run #7: crashed: general protection fault in free_netdev run #8: crashed: KASAN: use-after-free Read in netdevice_event_work_handler run #9: crashed: general protection fault in free_netdev run #10: crashed: KASAN: use-after-free Read in netdevice_event_work_handler run #11: crashed: KASAN: use-after-free Read in netdevice_event_work_handler run #12: crashed: general protection fault in free_netdev run #13: crashed: KASAN: use-after-free Read in netdevice_event_work_handler run #14: OK run #15: OK run #16: OK run #17: OK run #18: OK run #19: OK testing current HEAD 17ae69aba89dbfa2139b7f8024b757ab3cc42f59 testing commit 17ae69aba89dbfa2139b7f8024b757ab3cc42f59 with gcc (GCC) 10.2.1 20210217 kernel signature: 86655f9d3d29234b2a09812fec9549bd2cae18d874e290c4915c65eca0faf805 run #0: crashed: unregister_netdevice: waiting for DEV to become free run #1: crashed: WARNING in __nf_unregister_net_hook run #2: crashed: WARNING in __nf_unregister_net_hook run #3: OK run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK reproducer seems to be flaky Reproducer flagged being flaky revisions tested: 2, total time: 36m19.657392673s (build: 12m21.051518548s, test: 22m56.171489511s) the crash still happens on HEAD commit msg: Merge tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security crash: WARNING in __nf_unregister_net_hook ------------[ cut here ]------------ hook not found, pf 3 num 0 WARNING: CPU: 1 PID: 42 at net/netfilter/core.c:480 __nf_unregister_net_hook+0x17a/0x510 net/netfilter/core.c:480 Modules linked in: CPU: 0 PID: 42 Comm: kworker/u4:2 Not tainted 5.12.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net RIP: 0010:__nf_unregister_net_hook+0x17a/0x510 net/netfilter/core.c:480 Code: 89 f0 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 76 03 00 00 8b 53 1c 44 89 e6 48 c7 c7 60 33 7e 88 4c 89 04 24 e8 e3 f2 61 01 <0f> 0b 4c 8b 04 24 e9 9e 00 00 00 48 89 ea 48 c1 e2 04 49 8d 7c 10 RSP: 0018:ffffc900002c7bf0 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff888112a00c00 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000004 RDI: fffff52000058f70 RBP: 0000000000000001 R08: 0000000000000001 R09: ffff8881f652095b R10: ffffed103eca412b R11: fffffffffffd6970 R12: 0000000000000003 R13: ffff888122a82100 R14: ffff888112a00c1c R15: ffff888122a83020 FS: 0000000000000000(0000) GS:ffff8881f6400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f394c8ce000 CR3: 000000010b13c001 CR4: 00000000001706f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: nf_unregister_net_hook net/netfilter/core.c:502 [inline] nf_unregister_net_hooks+0xb1/0xf0 net/netfilter/core.c:576 ops_pre_exit_list net/core/net_namespace.c:165 [inline] cleanup_net+0x3a4/0x990 net/core/net_namespace.c:583 process_one_work+0x84c/0x13b0 kernel/workqueue.c:2275 worker_thread+0x598/0xf80 kernel/workqueue.c:2421 kthread+0x36f/0x450 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 irq event stamp: 92540271 hardirqs last enabled at (92540363): [] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline] hardirqs last enabled at (92540363): [] _raw_spin_unlock_irq+0x1f/0x80 kernel/locking/spinlock.c:199 hardirqs last disabled at (92540396): [] __schedule+0x1411/0x2400 kernel/sched/core.c:5043 softirqs last enabled at (92540688): [] invoke_softirq kernel/softirq.c:433 [inline] softirqs last enabled at (92540688): [] __irq_exit_rcu kernel/softirq.c:637 [inline] softirqs last enabled at (92540688): [] irq_exit_rcu+0x250/0x2a0 kernel/softirq.c:649 softirqs last disabled at (92540703): [] invoke_softirq kernel/softirq.c:433 [inline] softirqs last disabled at (92540703): [] __irq_exit_rcu kernel/softirq.c:637 [inline] softirqs last disabled at (92540703): [] irq_exit_rcu+0x250/0x2a0 kernel/softirq.c:649 ---[ end trace 91fc4643b2425616 ]--- netdevsim netdevsim2 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim2 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim2 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim2 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim4 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim4 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim4 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0