bisecting fixing commit since c14d30dc9987047b439b03d6e6db7d54d9f7f180 building syzkaller on e1c29030da37d46475ab5babe68abc4afe085799 testing commit c14d30dc9987047b439b03d6e6db7d54d9f7f180 with gcc (GCC) 8.1.0 kernel signature: 7cb77b6f5f834716afddd759ce97c3d68c9027dc525b1de055596b8f704fea54 all runs: crashed: divide error in tabledist testing current HEAD 015e94d0e37b6860e4354ce3cac56bd7c39c8992 testing commit 015e94d0e37b6860e4354ce3cac56bd7c39c8992 with gcc (GCC) 8.1.0 kernel signature: dd9200c1ba4b9d9b160518a2abbecb966de1d919d481c5a863c1e18c265736e3 all runs: crashed: divide error in tabledist revisions tested: 2, total time: 23m54.296187634s (build: 17m3.387575644s, test: 6m14.071920482s) the crash still happens on HEAD commit msg: Linux 4.19.146 crash: divide error in tabledist batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready batman_adv: batadv0: Interface activated: batadv_slave_1 divide error: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 3714 Comm: kworker/0:3 Not tainted 4.19.146-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.4+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:ffff88808f86ebf0 EFLAGS: 00010296 RAX: 0000000048bd0faf RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff876785a0 RDI: ffffffff8a1a5a60 RBP: ffff88808f86ec08 R08: 0000000000000001 R09: ffffed1011f0dd74 R10: ffffed1011f0dd74 R11: 0000000000000003 R12: 0000000000000000 R13: 0000000080000000 R14: ffff8880a8ed7b40 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc9b0f57000 CR3: 000000009ef63000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tabledist net/sched/sch_netem.c:534 [inline] netem_enqueue+0x421/0x2fb0 net/sched/sch_netem.c:534 __dev_xmit_skb net/core/dev.c:3494 [inline] __dev_queue_xmit+0x1098/0x2900 net/core/dev.c:3807 dev_queue_xmit+0xb/0x10 net/core/dev.c:3871 neigh_hh_output include/net/neighbour.h:491 [inline] neigh_output include/net/neighbour.h:499 [inline] ip_finish_output2+0x948/0x1290 net/ipv4/ip_output.c:229 ip_finish_output+0x402/0xb10 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip_output+0x1bc/0x530 net/ipv4/ip_output.c:405 dst_output include/net/dst.h:455 [inline] ip_local_out+0x74/0x110 net/ipv4/ip_output.c:124 iptunnel_xmit+0x5ae/0x950 net/ipv4/ip_tunnel_core.c:91 udp_tunnel_xmit_skb+0x23b/0x370 net/ipv4/udp_tunnel.c:182 geneve_xmit_skb drivers/net/geneve.c:857 [inline] geneve_xmit+0xedf/0x2a20 drivers/net/geneve.c:929 __netdev_start_xmit include/linux/netdevice.h:4333 [inline] netdev_start_xmit include/linux/netdevice.h:4347 [inline] xmit_one net/core/dev.c:3256 [inline] dev_hard_start_xmit+0x160/0x6e0 net/core/dev.c:3272 __dev_queue_xmit+0x1ca6/0x2900 net/core/dev.c:3838 dev_queue_xmit+0xb/0x10 net/core/dev.c:3871 neigh_resolve_output+0x4b5/0x830 net/core/neighbour.c:1374 neigh_output include/net/neighbour.h:501 [inline] ip6_finish_output2+0xf4e/0x2080 net/ipv6/ip6_output.c:120 ip6_finish_output+0x64e/0xa10 net/ipv6/ip6_output.c:154 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip6_output+0x1bb/0x610 net/ipv6/ip6_output.c:171 dst_output include/net/dst.h:455 [inline] NF_HOOK include/linux/netfilter.h:289 [inline] ndisc_send_skb+0x959/0x1340 net/ipv6/ndisc.c:491 ndisc_send_ns+0x42a/0x7e0 net/ipv6/ndisc.c:633 addrconf_dad_work+0x9df/0xf70 net/ipv6/addrconf.c:4075 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2155 worker_thread+0x85/0xb60 kernel/workqueue.c:2298 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Modules linked in: ---[ end trace 456e0397b8229b40 ]--- RIP: 0010:tabledist.part.4+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:ffff88808f86ebf0 EFLAGS: 00010296 RAX: 0000000048bd0faf RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff876785a0 RDI: ffffffff8a1a5a60 RBP: ffff88808f86ec08 R08: 0000000000000001 R09: ffffed1011f0dd74 R10: ffffed1011f0dd74 R11: 0000000000000003 R12: 0000000000000000 R13: 0000000080000000 R14: ffff8880a8ed7b40 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc9b0f57000 CR3: 000000009ef63000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Bluetooth: hci5: command 0x0419 tx timeout