bisecting fixing commit since 6dd0e32665e591e9debe3edaf73c2f8135bf047e building syzkaller on 17a986e54c507287c078a70fa9eea0be9f191f84 testing commit 6dd0e32665e591e9debe3edaf73c2f8135bf047e with gcc (GCC) 8.1.0 kernel signature: e96831eb8ddfcfc39971072793f93f725b256a70f8d8a5cd57e69468ed2f082a all runs: crashed: divide error in tabledist testing current HEAD c14d30dc9987047b439b03d6e6db7d54d9f7f180 testing commit c14d30dc9987047b439b03d6e6db7d54d9f7f180 with gcc (GCC) 8.1.0 kernel signature: db20664827e71932f9a18c0890d85380a91002b6f093b59b9edacc21c84fb1b1 all runs: crashed: divide error in tabledist revisions tested: 2, total time: 26m10.706018242s (build: 18m51.230724824s, test: 6m9.458805364s) the crash still happens on HEAD commit msg: Linux 4.19.139 crash: divide error in tabledist netlink: 32 bytes leftover after parsing attributes in process `syz-executor.3'. netlink: 17 bytes leftover after parsing attributes in process `syz-executor.5'. netlink: 32 bytes leftover after parsing attributes in process `syz-executor.5'. divide error: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.139-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:ffff8880aea074a0 EFLAGS: 00010296 RAX: 000000008dee927e RBX: 0000003e42c00000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff87679040 RDI: ffffffff8a18a960 RBP: ffff8880aea074b8 R08: 0000000000000001 R09: ffffed1015d40e8a R10: ffffed1015d40e8a R11: 0000000000000003 R12: 0000000000000000 R13: 0000000080000000 R14: ffff8880a9195b00 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000076c000 CR3: 000000009ec6f000 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+0x425/0x3020 net/sched/sch_netem.c:534 __dev_xmit_skb net/core/dev.c:3494 [inline] __dev_queue_xmit+0x10da/0x2a80 net/core/dev.c:3807 dev_queue_xmit+0xb/0x10 net/core/dev.c:3871 neigh_resolve_output+0x4ae/0x810 net/core/neighbour.c:1374 neigh_output include/net/neighbour.h:501 [inline] ip6_finish_output2+0x8f6/0x2200 net/ipv6/ip6_output.c:120 ip6_finish_output+0x3c6/0xa90 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:455 [inline] NF_HOOK include/linux/netfilter.h:289 [inline] ndisc_send_skb+0xcc8/0x12d0 net/ipv6/ndisc.c:491 ndisc_send_rs+0x116/0x5e0 net/ipv6/ndisc.c:685 addrconf_rs_timer+0x25c/0x5e0 net/ipv6/addrconf.c:3834 call_timer_fn+0x14c/0x510 kernel/time/timer.c:1338 expire_timers kernel/time/timer.c:1375 [inline] __run_timers kernel/time/timer.c:1703 [inline] run_timer_softirq+0xb63/0x1180 kernel/time/timer.c:1716 __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:544 [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:894 RIP: 0010:native_safe_halt+0x12/0x20 arch/x86/include/asm/irqflags.h:61 Code: 11 ff ff ff 4c 89 e7 e8 ac a5 b8 fa eb 97 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 e9 07 00 00 00 0f 00 2d 50 d0 4d 00 fb f4 <5d> c3 66 90 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 e9 07 00 00 RSP: 0018:ffffffff88407c88 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: ffffffff88479e40 RCX: 0000000000000000 RDX: 1ffffffff10a40bc RSI: 0000000000000001 RDI: ffffffff885205e0 RBP: ffffffff88407c88 R08: ffffed1015d44733 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff885205d0 R14: ffffffff8922e718 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline] default_idle+0x51/0x310 arch/x86/kernel/process.c:557 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:548 default_idle_call+0x6d/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x41e/0x560 kernel/sched/idle.c:263 cpu_startup_entry+0xc8/0xe0 kernel/sched/idle.c:369 rest_init+0x193/0x199 init/main.c:441 start_kernel+0x6a5/0x6e1 init/main.c:736 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490 x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:471 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 Modules linked in: ---[ end trace f5f23a28666bfaf0 ]--- divide error: 0000 [#2] PREEMPT SMP KASAN RIP: 0010:tabledist.part.18+0x10b/0x150 net/sched/sch_netem.c:333 CPU: 1 PID: 3684 Comm: systemd-journal Tainted: G D 4.19.139-syzkaller #0 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 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:ffff8880aeb074a0 EFLAGS: 00010296 RSP: 0018:ffff8880aea074a0 EFLAGS: 00010296 RAX: 0000000071186e4f RBX: 0000003e42c00000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff87679040 RDI: ffffffff8a18a960 RBP: ffff8880aeb074b8 R08: 0000000000000001 R09: ffffed1015d60e8a R10: ffffed1015d60e8a R11: 0000000000000003 R12: 0000000000000000 R13: 0000000080000000 R14: ffff8880a92b6000 R15: 0000000000000000 FS: 00007f4f412c08c0(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 RAX: 000000008dee927e RBX: 0000003e42c00000 RCX: 0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4f3e6a8018 CR3: 0000000095cc2000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: RDX: 0000000000000000 RSI: ffffffff87679040 RDI: ffffffff8a18a960 tabledist net/sched/sch_netem.c:534 [inline] netem_enqueue+0x425/0x3020 net/sched/sch_netem.c:534 RBP: ffff8880aea074b8 R08: 0000000000000001 R09: ffffed1015d40e8a R10: ffffed1015d40e8a R11: 0000000000000003 R12: 0000000000000000 __dev_xmit_skb net/core/dev.c:3494 [inline] __dev_queue_xmit+0x10da/0x2a80 net/core/dev.c:3807 R13: 0000000080000000 R14: ffff8880a9195b00 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000076c000 CR3: 000000009ec6f000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 dev_queue_xmit+0xb/0x10 net/core/dev.c:3871