bisecting fixing commit since e1f7d50ae3a3ec342e87a9b1ce6787bfb8b3c08b building syzkaller on be5c2c81971442d623dd1b265dabf4644ceeb35b testing commit e1f7d50ae3a3ec342e87a9b1ce6787bfb8b3c08b with gcc (GCC) 8.1.0 kernel signature: 18b9b1fe193287f90b77dd78b687d808f34b0649932b879c58f0ec62c58c155e all runs: crashed: divide error in netem_enqueue testing current HEAD 8bac50406cca10a219aa899243d49c57ddaf7c5b testing commit 8bac50406cca10a219aa899243d49c57ddaf7c5b with gcc (GCC) 8.1.0 kernel signature: b25f2f73157550432b08ff26e21e93011c2819e0a09d921c34ee8d6e16acbf8c all runs: crashed: divide error in netem_enqueue revisions tested: 2, total time: 25m48.639602548s (build: 17m25.933186675s, test: 7m50.99050082s) the crash still happens on HEAD commit msg: Linux 4.14.167 crash: divide error in netem_enqueue IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready device hsr_slave_0 entered promiscuous mode device hsr_slave_1 entered promiscuous mode divide error: 0000 [#1] PREEMPT SMP KASAN Modules linked in: CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 4.14.167-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 8021q: adding VLAN 0 to HW filter on device bond0 task: ffff8880a9cd61c0 task.stack: ffff8880a9ce8000 IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready RIP: 0010:packet_len_2_sched_time net/sched/sch_netem.c:352 [inline] RIP: 0010:netem_enqueue+0x6f9/0x28b0 net/sched/sch_netem.c:561 RSP: 0018:ffff8880a9ceeb30 EFLAGS: 00010246 IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready RAX: 1aedcbe189692000 RBX: ffff888097ff2b3c RCX: 000000000000001e RDX: 0000000000000000 RSI: 000000003668884d RDI: ffff888097ff2b68 RBP: ffff8880a9ceebc0 R08: ffff888097ff2ac0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000073a8a150 R13: 0000000073000000 R14: 000000000000206e R15: ffff888097ff2900 FS: 0000000000000000(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc18aa9f000 CR3: 000000009f546000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 IPv6: ADDRCONF(NETDEV_UP): team0: link is not ready DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __dev_xmit_skb net/core/dev.c:3229 [inline] __dev_queue_xmit+0x1156/0x2740 net/core/dev.c:3493 8021q: adding VLAN 0 to HW filter on device team0 IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready dev_queue_xmit+0xb/0x10 net/core/dev.c:3558 IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready br_dev_queue_push_xmit+0x14b/0x570 net/bridge/br_forward.c:55 IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready br_nf_dev_queue_xmit+0x2a9/0x1740 net/bridge/br_netfilter_hooks.c:779 NF_HOOK include/linux/netfilter.h:250 [inline] br_nf_post_routing+0x5e8/0xdc0 net/bridge/br_netfilter_hooks.c:825 IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready nf_hook_entry_hookfn include/linux/netfilter.h:108 [inline] nf_hook_slow+0xa1/0x180 net/netfilter/core.c:467 nf_hook include/linux/netfilter.h:205 [inline] NF_HOOK include/linux/netfilter.h:248 [inline] br_forward_finish+0x18a/0x2b0 net/bridge/br_forward.c:67 IPv6: ADDRCONF(NETDEV_UP): veth0_to_hsr: link is not ready br_nf_hook_thresh+0x23b/0x380 net/bridge/br_netfilter_hooks.c:1008 IPv6: ADDRCONF(NETDEV_UP): veth1_to_hsr: link is not ready hsr0: Slave A (hsr_slave_0) is not up; please bring it up to get a fully working HSR network br_nf_forward_finish+0x22a/0x630 net/bridge/br_netfilter_hooks.c:550 hsr0: Slave B (hsr_slave_1) is not up; please bring it up to get a fully working HSR network NF_HOOK include/linux/netfilter.h:250 [inline] br_nf_forward_ip+0x555/0x1440 net/bridge/br_netfilter_hooks.c:617 IPv6: ADDRCONF(NETDEV_UP): hsr0: link is not ready nf_hook_entry_hookfn include/linux/netfilter.h:108 [inline] nf_hook_slow+0xa1/0x180 net/netfilter/core.c:467 nf_hook include/linux/netfilter.h:205 [inline] NF_HOOK include/linux/netfilter.h:248 [inline] __br_forward+0x2be/0x8d0 net/bridge/br_forward.c:111 IPv6: ADDRCONF(NETDEV_UP): vxcan0: link is not ready IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready deliver_clone+0x54/0xa0 net/bridge/br_forward.c:127 br_flood+0x36d/0x4f0 net/bridge/br_forward.c:222 8021q: adding VLAN 0 to HW filter on device batadv0 br_handle_frame_finish+0xa69/0x1db0 net/bridge/br_input.c:210 br_nf_hook_thresh+0x23b/0x380 net/bridge/br_netfilter_hooks.c:1008 br_nf_pre_routing_finish_ipv6+0x5cb/0xb10 net/bridge/br_netfilter_ipv6.c:210 NF_HOOK include/linux/netfilter.h:250 [inline] br_nf_pre_routing_ipv6+0x3de/0x700 net/bridge/br_netfilter_ipv6.c:240 br_nf_pre_routing+0x848/0x11b0 net/bridge/br_netfilter_hooks.c:491 nf_hook_entry_hookfn include/linux/netfilter.h:108 [inline] nf_hook_slow+0xa1/0x180 net/netfilter/core.c:467 nf_hook include/linux/netfilter.h:205 [inline] NF_HOOK include/linux/netfilter.h:248 [inline] br_handle_frame+0x762/0x1180 net/bridge/br_input.c:348 __netif_receive_skb_core+0x6d1/0x3260 net/core/dev.c:4431 __netif_receive_skb+0x1f/0x1b0 net/core/dev.c:4515 process_backlog+0x1fc/0x710 net/core/dev.c:5197 napi_poll net/core/dev.c:5598 [inline] net_rx_action+0x458/0xed0 net/core/dev.c:5664 __do_softirq+0x246/0x9b0 kernel/softirq.c:288 run_ksoftirqd+0x92/0x1a0 kernel/softirq.c:670 smpboot_thread_fn+0x553/0x850 kernel/smpboot.c:164 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Code: 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e ce 20 00 00 41 8b 87 68 02 00 00 44 01 e8 44 0f af e0 49 69 c4 00 ca 9a 3b 45 89 d2 31 d2 <49> f7 f2 48 c1 e8 06 49 01 c3 48 8b 45 d0 49 01 f3 48 8d 78 30 RIP: packet_len_2_sched_time net/sched/sch_netem.c:352 [inline] RSP: ffff8880a9ceeb30 RIP: netem_enqueue+0x6f9/0x28b0 net/sched/sch_netem.c:561 RSP: ffff8880a9ceeb30 ---[ end trace 6700c4018f9b1632 ]---