bisecting fixing commit since c3038e718a19fc596f7b1baba0f83d5146dc7784 building syzkaller on 25bb509e5964da8203766c4039e4fef25e4689b1 testing commit c3038e718a19fc596f7b1baba0f83d5146dc7784 with gcc (GCC) 8.1.0 kernel signature: e7c49ab3df5a8afc31a099fb6d108c2b29a309a9 all runs: crashed: divide error in tabledist testing current HEAD 312017a460d5ea31d646e7148e400e13db799ddc testing commit 312017a460d5ea31d646e7148e400e13db799ddc with gcc (GCC) 8.1.0 kernel signature: bb6d25501102aa8730403390f111f2ded73339ad all runs: crashed: divide error in tabledist revisions tested: 2, total time: 24m45.44255184s (build: 17m5.469147689s, test: 6m42.193163531s) the crash still happens on HEAD commit msg: Linux 4.19.89 crash: divide error in tabledist IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_0: link becomes ready IPv6: ADDRCONF(NETDEV_UP): veth1_to_hsr: link is not ready IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready divide error: 0000 [#1] PREEMPT SMP KASAN IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready CPU: 1 PID: 18 Comm: ksoftirqd/1 Not tainted 4.19.89-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:ffff8880aa3a6a28 EFLAGS: 00010286 RAX: 00000000e0464d16 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff86ff1360 RDI: ffffffff89a7e6e0 RBP: ffff8880aa3a6a40 R08: 0000000000000001 R09: 0000000000000000 R10: ffffed1013067665 R11: ffff88809833b32b R12: 0000000000000000 R13: 0000000080000000 R14: ffff8880a03b0640 R15: ffff88809833b240 FS: 0000000000000000(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fcf3eeba330 CR3: 000000008d376000 CR4: 00000000001406e0 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:3495 [inline] __dev_queue_xmit+0x10ce/0x2a90 net/core/dev.c:3811 dev_queue_xmit+0xb/0x10 net/core/dev.c:3876 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:779 NF_HOOK include/linux/netfilter.h:289 [inline] br_nf_post_routing+0x8c6/0xec0 net/bridge/br_netfilter_hooks.c:825 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:1008 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:1008 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+0xc06/0x3010 net/core/dev.c:4875 __netif_receive_skb_one_core+0x99/0x170 net/core/dev.c:4944 __netif_receive_skb+0x1f/0x1b0 net/core/dev.c:5058 process_backlog+0x1ca/0x6d0 net/core/dev.c:5869 napi_poll net/core/dev.c:6292 [inline] net_rx_action+0x470/0xe20 net/core/dev.c:6358 __do_softirq+0x260/0x92d kernel/softirq.c:292 run_ksoftirqd+0x94/0x100 kernel/softirq.c:653 smpboot_thread_fn+0x55f/0x8a0 kernel/smpboot.c:164 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Modules linked in: ---[ end trace 3bd366038c10daec ]--- RIP: 0010:tabledist.part.18+0x10b/0x150 net/sched/sch_netem.c:333 divide error: 0000 [#2] PREEMPT SMP KASAN 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 CPU: 0 PID: 0 Comm: swapper/0 Tainted: G D 4.19.89-syzkaller #0 RSP: 0018:ffff8880aa3a6a28 EFLAGS: 00010286 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 RAX: 00000000e0464d16 RBX: 0000000000000000 RCX: 0000000000000000 RSP: 0018:ffff8880aea06fb8 EFLAGS: 00010286 RDX: 0000000000000000 RSI: ffffffff86ff1360 RDI: ffffffff89a7e6e0 RAX: 00000000152d66e9 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff86ff1360 RDI: ffffffff89a7e6e0 RBP: ffff8880aea06fd0 R08: 0000000000000001 R09: 0000000000000000 R10: ffffed1013067545 R11: ffff88809833aa2b R12: 0000000000000000 R13: 0000000080000000 R14: ffff8880987a9500 R15: ffff88809833a940 FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000265b000 CR3: 0000000097e87000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 RBP: ffff8880aa3a6a40 R08: 0000000000000001 R09: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 R10: ffffed1013067665 R11: ffff88809833b32b R12: 0000000000000000 Call Trace: tabledist net/sched/sch_netem.c:533 [inline] netem_enqueue+0x3a3/0x2770 net/sched/sch_netem.c:533 R13: 0000000080000000 R14: ffff8880a03b0640 R15: ffff88809833b240 __dev_xmit_skb net/core/dev.c:3495 [inline] __dev_queue_xmit+0x10ce/0x2a90 net/core/dev.c:3811 FS: 0000000000000000(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fcf3eeba330 CR3: 000000008d376000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 dev_queue_xmit+0xb/0x10 net/core/dev.c:3876 br_dev_queue_push_xmit+0x14b/0x590 net/bridge/br_forward.c:56 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400