bisecting fixing commit since c3038e718a19fc596f7b1baba0f83d5146dc7784 building syzkaller on 25bb509e5964da8203766c4039e4fef25e4689b1 testing commit c3038e718a19fc596f7b1baba0f83d5146dc7784 with gcc (GCC) 8.1.0 kernel signature: d6dbc3effc1b39f09290119e5fb496ed1fd1cdb2 all runs: crashed: divide error in tabledist testing current HEAD dcd888983542055210f5e68f1b1f1f8fe11a369a testing commit dcd888983542055210f5e68f1b1f1f8fe11a369a with gcc (GCC) 8.1.0 kernel signature: 683b608b1d673e4f0b89e31035476fef7be177f9 all runs: crashed: divide error in tabledist revisions tested: 2, total time: 24m31.947003878s (build: 17m13.510070876s, test: 6m24.313813219s) the crash still happens on HEAD commit msg: Linux 4.19.95 crash: divide error in tabledist IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_team: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): team_slave_0: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): team0: link becomes ready 8021q: adding VLAN 0 to HW filter on device batadv0 divide error: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 7168 Comm: syz-executor.3 Not tainted 4.19.95-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 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:ffff8880aea06f98 EFLAGS: 00010282 RAX: 00000000dc2bb00d RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff86ff15e0 RDI: ffffffff89a7e6e0 RBP: ffff8880aea06fb0 R08: 0000000000000001 R09: 0000000000000000 R10: ffffed1011293265 R11: ffff88808949932b R12: 0000000000000000 R13: 0000000080000000 R14: ffff88808af84900 R15: ffff888089499240 FS: 0000000000bfc940(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000075c000 CR3: 00000000904d2000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tabledist net/sched/sch_netem.c:533 [inline] netem_enqueue+0x3a3/0x2770 net/sched/sch_netem.c:533 __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 NF_HOOK include/linux/netfilter.h:289 [inline] br_forward_finish+0xdd/0x2f0 net/bridge/br_forward.c:69 NF_HOOK include/linux/netfilter.h:289 [inline] __br_forward+0x4d1/0x8d0 net/bridge/br_forward.c:113 deliver_clone+0x54/0xa0 net/bridge/br_forward.c:129 maybe_deliver net/bridge/br_forward.c:184 [inline] br_flood+0x3a4/0x580 net/bridge/br_forward.c:226 br_dev_xmit+0xc5c/0x1210 net/bridge/br_device.c:103 __netdev_start_xmit include/linux/netdevice.h:4312 [inline] netdev_start_xmit include/linux/netdevice.h:4321 [inline] xmit_one net/core/dev.c:3258 [inline] dev_hard_start_xmit+0x160/0x6f0 net/core/dev.c:3274 __dev_queue_xmit+0x2135/0x2a90 net/core/dev.c:3844 dev_queue_xmit+0xb/0x10 net/core/dev.c:3877 neigh_hh_output include/net/neighbour.h:491 [inline] neigh_output include/net/neighbour.h:499 [inline] ip6_finish_output2+0xf33/0x2310 net/ipv6/ip6_output.c:120 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_cr net/ipv6/mcast.c:1980 [inline] mld_ifc_timer_expire+0x367/0x760 net/ipv6/mcast.c:2479 call_timer_fn+0x14c/0x510 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers kernel/time/timer.c:1684 [inline] run_timer_softirq+0xb63/0x1180 kernel/time/timer.c:1697 __do_softirq+0x260/0x92d kernel/softirq.c:292 invoke_softirq kernel/softirq.c:372 [inline] irq_exit+0x17f/0x1c0 kernel/softirq.c:412 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x13e/0x540 arch/x86/kernel/apic/apic.c:1094 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:893 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline] RIP: 0010:console_unlock+0x904/0xde0 kernel/printk/printk.c:2437 Code: 00 fc ff df 48 89 f8 48 c1 e8 03 42 80 3c 18 00 0f 85 96 03 00 00 48 83 3d 20 67 a4 06 00 0f 84 08 02 00 00 48 8b 7d c8 57 9d <0f> 1f 44 00 00 e9 5d f8 ff ff 49 8d 7e 08 48 89 f8 48 c1 e8 03 42 RSP: 0018:ffff888093286a68 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff0fe40e9 RBX: 0000000000000200 RCX: 1ffff11011aaa559 RDX: 0000000000000000 RSI: ffff88808d552aa8 RDI: 0000000000000282 RBP: ffff888093286ae0 R08: ffff88808d552ac8 R09: 0000000000000000 R10: 0000000000000000 R11: dffffc0000000000 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff885323e0 R15: ffffffff885323b0 vprintk_emit+0x191/0x540 kernel/printk/printk.c:1937 vprintk_default+0x1a/0x20 kernel/printk/printk.c:1979 vprintk_func+0x49/0x12c kernel/printk/printk_safe.c:398 printk+0x9a/0xc0 kernel/printk/printk.c:2012 vlan_device_event.cold.12+0x16/0x2a net/8021q/vlan.c:379 notifier_call_chain+0x8a/0x160 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x11/0x20 kernel/notifier.c:401 call_netdevice_notifiers_info+0x28/0x60 net/core/dev.c:1748 call_netdevice_notifiers net/core/dev.c:1766 [inline] __dev_notify_flags+0xda/0x240 net/core/dev.c:7730 dev_change_flags+0xe6/0x150 net/core/dev.c:7766 do_setlink+0x1173/0x2d20 net/core/rtnetlink.c:2449 rtnl_newlink+0xa18/0x1310 net/core/rtnetlink.c:3068 rtnetlink_rcv_msg+0x34f/0x8f0 net/core/rtnetlink.c:4768 netlink_rcv_skb+0x142/0x390 net/netlink/af_netlink.c:2454 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4786 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline] netlink_unicast+0x445/0x640 net/netlink/af_netlink.c:1343 netlink_sendmsg+0x765/0xc50 net/netlink/af_netlink.c:1908 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xb5/0xf0 net/socket.c:632 __sys_sendto+0x1f2/0x2e0 net/socket.c:1787 __do_sys_sendto net/socket.c:1799 [inline] __se_sys_sendto net/socket.c:1795 [inline] __x64_sys_sendto+0xdc/0x1a0 net/socket.c:1795 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x413c33 Code: ff 0f 83 b0 19 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d dd 43 66 00 00 75 17 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 81 19 00 00 c3 48 83 ec 08 e8 87 fa ff ff RSP: 002b:00007ffd37af8858 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000413c33 RDX: 0000000000000038 RSI: 0000000000a71df0 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007ffd37af8860 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000006 R13: 0000000000000003 R14: 00007ffd37af8908 R15: 0000000000000006 Modules linked in: ---[ end trace 3b668dab43ceaa8a ]--- 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:ffff8880aea06f98 EFLAGS: 00010282 RAX: 00000000dc2bb00d RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff86ff15e0 RDI: ffffffff89a7e6e0 RBP: ffff8880aea06fb0 R08: 0000000000000001 R09: 0000000000000000 R10: ffffed1011293265 R11: ffff88808949932b R12: 0000000000000000 R13: 0000000080000000 R14: ffff88808af84900 R15: ffff888089499240 FS: 0000000000bfc940(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000075c000 CR3: 00000000904d2000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400