bisecting fixing commit since c3038e718a19fc596f7b1baba0f83d5146dc7784 building syzkaller on 25bb509e5964da8203766c4039e4fef25e4689b1 testing commit c3038e718a19fc596f7b1baba0f83d5146dc7784 with gcc (GCC) 8.1.0 kernel signature: 11ca891f3a0ec4ee4e28851619227400dabbe871c501c0f469f36e6cd7c30df5 all runs: crashed: divide error in tabledist testing current HEAD dda0e2920330128e0dbdeb11c8f25031aa40b11c testing commit dda0e2920330128e0dbdeb11c8f25031aa40b11c with gcc (GCC) 8.1.0 kernel signature: b4da0967d63675fdebf68d3670dec32d1c91a4380709b557543c7cda05b58bba all runs: crashed: divide error in tabledist revisions tested: 2, total time: 24m34.912158318s (build: 17m30.650900787s, test: 6m1.25275608s) the crash still happens on HEAD commit msg: Linux 4.19.114 crash: divide error in tabledist IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_0: link becomes ready IPv6: ADDRCONF(NETDEV_UP): hsr0: link is not ready IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready divide error: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 2819 Comm: kworker/1:2 Not tainted 4.19.114-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: ipv6_addrconf addrconf_dad_work RIP: 0010:tabledist.part.18+0x10b/0x150 net/sched/sch_netem.c:333 Code: 3c 18 49 8d 80 ff 1f 00 00 49 0f 49 c0 48 83 c4 08 5b 48 c1 f8 0d 41 5c 48 01 f8 41 5d 5d c3 43 8d 4c 2d 00 31 d2 48 83 c4 08 f1 49 63 c5 48 29 c3 48 8d 04 1a 5b 41 5c 41 5d 5d c3 4c 89 e7 RSP: 0018:ffff8880aeb06bd8 EFLAGS: 00010286 RAX: 00000000b258f331 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff86ff1ba0 RDI: ffffffff89a816e0 RBP: ffff8880aeb06bf0 R08: 0000000000000001 R09: ffffed1012e44425 R10: ffffed1012e44425 R11: ffff88809722212b R12: 0000000000000000 R13: 0000000080000000 R14: ffff888097222040 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fffa571fc70 CR3: 000000008ed06000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tabledist net/sched/sch_netem.c:534 [inline] netem_enqueue+0x3b0/0x27a0 net/sched/sch_netem.c:534 __dev_xmit_skb net/core/dev.c:3496 [inline] __dev_queue_xmit+0x10ce/0x2a90 net/core/dev.c:3812 dev_queue_xmit+0xb/0x10 net/core/dev.c:3877 br_dev_queue_push_xmit+0x14b/0x590 net/bridge/br_forward.c:56 br_nf_dev_queue_xmit+0x2a7/0x1560 net/bridge/br_netfilter_hooks.c:782 NF_HOOK include/linux/netfilter.h:289 [inline] br_nf_post_routing+0x8c6/0xec0 net/bridge/br_netfilter_hooks.c:828 nf_hook_entry_hookfn include/linux/netfilter.h:119 [inline] nf_hook_slow+0xa1/0x180 net/netfilter/core.c:511 nf_hook include/linux/netfilter.h:244 [inline] NF_HOOK include/linux/netfilter.h:287 [inline] br_forward_finish+0x1b5/0x2f0 net/bridge/br_forward.c:69 br_nf_hook_thresh+0x269/0x3b0 net/bridge/br_netfilter_hooks.c:1011 br_nf_forward_finish+0x2cc/0x660 net/bridge/br_netfilter_hooks.c:553 NF_HOOK include/linux/netfilter.h:289 [inline] br_nf_forward_ip+0x7d6/0x17f0 net/bridge/br_netfilter_hooks.c:620 nf_hook_entry_hookfn include/linux/netfilter.h:119 [inline] nf_hook_slow+0xa1/0x180 net/netfilter/core.c:511 nf_hook include/linux/netfilter.h:244 [inline] NF_HOOK include/linux/netfilter.h:287 [inline] __br_forward+0x2ad/0x8d0 net/bridge/br_forward.c:113 deliver_clone+0x54/0xa0 net/bridge/br_forward.c:129 br_flood+0x426/0x580 net/bridge/br_forward.c:238 br_handle_frame_finish+0xd8b/0x15a0 net/bridge/br_input.c:167 br_nf_hook_thresh+0x269/0x3b0 net/bridge/br_netfilter_hooks.c:1011 br_nf_pre_routing_finish_ipv6+0x629/0xba0 net/bridge/br_netfilter_ipv6.c:210 NF_HOOK include/linux/netfilter.h:289 [inline] br_nf_pre_routing_ipv6+0x43e/0x779 net/bridge/br_netfilter_ipv6.c:240 br_nf_pre_routing+0x89d/0x11e1 net/bridge/br_netfilter_hooks.c:494 nf_hook_entry_hookfn include/linux/netfilter.h:119 [inline] nf_hook_slow+0xa1/0x180 net/netfilter/core.c:511 nf_hook include/linux/netfilter.h:244 [inline] NF_HOOK include/linux/netfilter.h:287 [inline] br_handle_frame+0x79a/0x116e net/bridge/br_input.c:306 __netif_receive_skb_core+0xc6b/0x31c0 net/core/dev.c:4876 __netif_receive_skb_one_core+0x99/0x170 net/core/dev.c:4945 __netif_receive_skb+0x1f/0x1b0 net/core/dev.c:5059 process_backlog+0x1ca/0x6d0 net/core/dev.c:5841 napi_poll net/core/dev.c:6264 [inline] net_rx_action+0x470/0xe20 net/core/dev.c:6330 __do_softirq+0x260/0x92d kernel/softirq.c:292 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1091 do_softirq.part.13+0x126/0x160 kernel/softirq.c:336 do_softirq kernel/softirq.c:328 [inline] __local_bh_enable_ip+0x21d/0x260 kernel/softirq.c:189 local_bh_enable include/linux/bottom_half.h:32 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:721 [inline] ip6_finish_output2+0x947/0x2310 net/ipv6/ip6_output.c:121 ip6_finish_output+0x3c4/0xa90 net/ipv6/ip6_output.c:154 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip6_output+0x1bf/0x660 net/ipv6/ip6_output.c:171 dst_output include/net/dst.h:447 [inline] NF_HOOK include/linux/netfilter.h:289 [inline] mld_sendpack+0x87c/0xcd0 net/ipv6/mcast.c:1684 mld_send_initial_cr.part.32+0xd7/0x110 net/ipv6/mcast.c:2101 mld_send_initial_cr net/ipv6/mcast.c:2114 [inline] ipv6_mc_dad_complete+0x14d/0x1a0 net/ipv6/mcast.c:2108 addrconf_dad_completed+0x86f/0xbb0 net/ipv6/addrconf.c:4127 addrconf_dad_work+0x652/0xfc0 net/ipv6/addrconf.c:4058 process_one_work+0x830/0x1670 kernel/workqueue.c:2155 worker_thread+0x85/0xb60 kernel/workqueue.c:2298 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Modules linked in: ---[ end trace 864aa9ece1b88856 ]--- RIP: 0010:tabledist.part.18+0x10b/0x150 net/sched/sch_netem.c:333 Code: 3c 18 49 8d 80 ff 1f 00 00 49 0f 49 c0 48 83 c4 08 5b 48 c1 f8 0d 41 5c 48 01 f8 41 5d 5d c3 43 8d 4c 2d 00 31 d2 48 83 c4 08 f1 49 63 c5 48 29 c3 48 8d 04 1a 5b 41 5c 41 5d 5d c3 4c 89 e7 RSP: 0018:ffff8880aeb06bd8 EFLAGS: 00010286 RAX: 00000000b258f331 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff86ff1ba0 RDI: ffffffff89a816e0 RBP: ffff8880aeb06bf0 R08: 0000000000000001 R09: ffffed1012e44425 R10: ffffed1012e44425 R11: ffff88809722212b R12: 0000000000000000 R13: 0000000080000000 R14: ffff888097222040 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fffa571fc70 CR3: 0000000007e6d000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400