bisecting fixing commit since f116b96685a046a89c25d4a6ba2da489145c8888 building syzkaller on d01bb02a96019cda0fa8c46e5c6d5eb66a273f17 testing commit f116b96685a046a89c25d4a6ba2da489145c8888 with gcc (GCC) 8.1.0 kernel signature: c426b482d0cf5432f8c44294ea8782246a22d7b7 all runs: crashed: divide error in tabledist testing current HEAD bef1d88263ff769f15aa0e1515cdcede84e61d15 testing commit bef1d88263ff769f15aa0e1515cdcede84e61d15 with gcc (GCC) 8.1.0 kernel signature: 3dbe503e796312edb6d42f9a638fa7348b1c972f all runs: crashed: divide error in tabledist revisions tested: 2, total time: 19m19.692942685s (build: 11m59.931345206s, test: 6m42.044102178s) the crash still happens on HEAD commit msg: Merge tag 'pstore-v5.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux crash: divide error in tabledist divide error: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.5.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:tabledist.part.20+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:ffff8880a9d3ea78 EFLAGS: 00010286 RAX: 00000000aa3dac69 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000080000000 RDI: ffffffff89ff78a0 RBP: ffff8880a9d3ea90 R08: 0000000000000001 R09: ffff888095710dc0 R10: ffffed10132e562e R11: ffff88809972b177 R12: 0000000000000000 R13: 0000000080000000 R14: ffff88809972b000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6be1b06000 CR3: 0000000097670000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tabledist net/sched/sch_netem.c:536 [inline] netem_enqueue+0xdae/0x2f40 net/sched/sch_netem.c:536 __dev_xmit_skb net/core/dev.c:3671 [inline] __dev_queue_xmit+0x103e/0x2e80 net/core/dev.c:3982 dev_queue_xmit+0xb/0x10 net/core/dev.c:4046 br_dev_queue_push_xmit+0x14b/0x560 net/bridge/br_forward.c:52 br_nf_dev_queue_xmit+0x293/0x15d0 net/bridge/br_netfilter_hooks.c:803 NF_HOOK include/linux/netfilter.h:307 [inline] br_nf_post_routing+0xfbb/0x1690 net/bridge/br_netfilter_hooks.c:851 nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline] nf_hook_slow+0xa3/0x170 net/netfilter/core.c:512 nf_hook include/linux/netfilter.h:262 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] br_forward_finish+0x1b5/0x2f0 net/bridge/br_forward.c:65 br_nf_hook_thresh+0x269/0x3b0 net/bridge/br_netfilter_hooks.c:1022 br_nf_forward_finish+0x589/0x8b0 net/bridge/br_netfilter_hooks.c:564 NF_HOOK include/linux/netfilter.h:307 [inline] br_nf_forward_ip+0x986/0x1a00 net/bridge/br_netfilter_hooks.c:634 nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline] nf_hook_slow+0xa3/0x170 net/netfilter/core.c:512 nf_hook include/linux/netfilter.h:262 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] __br_forward+0x2ad/0x890 net/bridge/br_forward.c:109 deliver_clone+0x54/0xa0 net/bridge/br_forward.c:125 br_flood+0x23d/0x2f0 net/bridge/br_forward.c:232 br_handle_frame_finish+0x9aa/0x16d0 net/bridge/br_input.c:162 br_nf_hook_thresh+0x269/0x3b0 net/bridge/br_netfilter_hooks.c:1022 br_nf_pre_routing_finish_ipv6+0x618/0xb70 net/bridge/br_netfilter_ipv6.c:206 NF_HOOK include/linux/netfilter.h:307 [inline] br_nf_pre_routing_ipv6+0x3dd/0x6e0 net/bridge/br_netfilter_ipv6.c:236 br_nf_pre_routing+0x12a3/0x1b43 net/bridge/br_netfilter_hooks.c:505 nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline] nf_hook_bridge_pre net/bridge/br_input.c:224 [inline] br_handle_frame+0x69e/0x10c0 net/bridge/br_input.c:349 __netif_receive_skb_core+0xe0d/0x2b20 net/core/dev.c:5051 __netif_receive_skb_one_core+0x99/0x170 net/core/dev.c:5148 __netif_receive_skb+0x1f/0x1b0 net/core/dev.c:5264 process_backlog+0x1ca/0x6d0 net/core/dev.c:6095 napi_poll net/core/dev.c:6532 [inline] net_rx_action+0x458/0xe40 net/core/dev.c:6600 __do_softirq+0x262/0x9a8 kernel/softirq.c:292 run_ksoftirqd+0x94/0x100 kernel/softirq.c:603 smpboot_thread_fn+0x55f/0x8b0 kernel/smpboot.c:165 kthread+0x331/0x3f0 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Modules linked in: ---[ end trace cc9a3cd2e8bf9067 ]--- RIP: 0010:tabledist.part.20+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:ffff8880a9d3ea78 EFLAGS: 00010286 RAX: 00000000aa3dac69 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000080000000 RDI: ffffffff89ff78a0 RBP: ffff8880a9d3ea90 R08: 0000000000000001 R09: ffff888095710dc0 R10: ffffed10132e562e R11: ffff88809972b177 R12: 0000000000000000 R13: 0000000080000000 R14: ffff88809972b000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6be1b06000 CR3: 0000000097670000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400