Hi Anand, Thanks for reporting this bug.
Could you please try the kernel version in xenial-proposed? [1] (version: 4.4.0-185.215) It has a patch for what seems to be this problem, according to the stack trace seen in apport's kernel crash dump below. The patch is: 'net: handle no dst on skb in icmp6_send' [1] https://wiki.ubuntu.com/Testing/EnableProposed cheers, Mauricio ... The stacktrace from apport's 'kernel crash dump' attachment (linux-image-4.4.0-184-generic-202006151751.crash): $ apport-unpack linux-image-4.4.0-184-generic-202006151751.crash k/ $ ls k Architecture Date DistroRelease Package ProblemType Uname VmCoreDmesg $ cat k/VmCoreDmesg ... [ 13.702003] nf_conntrack version 0.5.0 (16384 buckets, 65536 max) [ 962.936170] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 [ 962.936250] IP: [<ffffffff818288ab>] icmp6_send+0x1fb/0x970 [ 962.936296] PGD 0 [ 962.936314] Oops: 0000 [#1] SMP [ 962.936341] Modules linked in: xt_tcpudp nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack iptable_filter ip_tables x_tables vmw_vsock_vmci_transport vsock coretemp ppdev vmw_balloon input_leds joydev serio_raw shpchp vmw_vmci i2c_piix4 8250_fintek parport_pc mac_hid lp parport autofs4 xfs libcrc32c vmwgfx psmouse ttm drm_kms_helper syscopyarea sysfillrect mptspi sysimgblt mptscsih fb_sys_fops mptbase drm vmxnet3 scsi_transport_spi pata_acpi floppy fjes [ 962.936723] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.4.0-184-generic #214-Ubuntu [ 962.936775] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 09/17/2015 [ 962.936844] task: ffff88013a562700 ti: ffff88013a570000 task.ti: ffff88013a570000 [ 962.936893] RIP: 0010:[<ffffffff818288ab>] [<ffffffff818288ab>] icmp6_send+0x1fb/0x970 [ 962.936950] RSP: 0018:ffff88013fd83d00 EFLAGS: 00010246 [ 962.936986] RAX: 0000000000000000 RBX: ffff880139f88a00 RCX: 0000000000000020 [ 962.937032] RDX: 0000000000000001 RSI: 0000000000000200 RDI: ffff8800b8448fd6 [ 962.937079] RBP: ffff88013fd83e20 R08: 0000000000000000 R09: ffff8800b8448fe6 [ 962.937126] R10: 0000000000000080 R11: 0000000000000000 R12: ffff8800b8448fce [ 962.937172] R13: ffffffff81efb6c0 R14: 0000000000000001 R15: 0000000000000003 [ 962.937219] FS: 0000000000000000(0000) GS:ffff88013fd80000(0000) knlGS:0000000000000000 [ 962.937272] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 962.937310] CR2: 0000000000000018 CR3: 00000000ba602000 CR4: 0000000000000670 [ 962.937429] Stack: [ 962.937448] 0000000000000000 0000000000000000 000000e032fd4a6a ffff88010026d82b [ 962.937505] ffffffff810baaea ffff88013fd963b0 0000000000000000 ffff8800b8448fd6 [ 962.937565] ffff880100000001 0000000000000000 ffff8800b8448fe6 ffffffff810c077a [ 962.937623] Call Trace: [ 962.937642] <IRQ> [ 962.937664] [<ffffffff810baaea>] ? select_idle_sibling+0x2a/0x120 [ 962.937708] [<ffffffff810c077a>] ? enqueue_task_fair+0xaa/0x8b0 [ 962.937753] [<ffffffff81038119>] ? sched_clock+0x9/0x10 [ 962.937790] [<ffffffff810b8c8f>] ? sched_clock_cpu+0x8f/0xa0 [ 962.937832] [<ffffffff810b2524>] ? check_preempt_curr+0x54/0x90 [ 962.939091] [<ffffffff81868280>] ? _raw_spin_unlock_bh+0x20/0x50 [ 962.940307] [<ffffffff81841ed1>] icmpv6_send+0x21/0x30 [ 962.941522] [<ffffffff8182fe95>] ip6_expire_frag_queue+0x115/0x1b0 [ 962.942710] [<ffffffff8182ff30>] ? ip6_expire_frag_queue+0x1b0/0x1b0 [ 962.943892] [<ffffffff8182ff4f>] ip6_frag_expire+0x1f/0x30 [ 962.945057] [<ffffffff810f57c7>] call_timer_fn+0x37/0x140 [ 962.946241] [<ffffffff8182ff30>] ? ip6_expire_frag_queue+0x1b0/0x1b0 [ 962.947410] [<ffffffff810f70d4>] run_timer_softirq+0x234/0x330 [ 962.948537] [<ffffffff8108b509>] __do_softirq+0x109/0x2b0 [ 962.949638] [<ffffffff8108b825>] irq_exit+0xa5/0xb0 [ 962.950696] [<ffffffff8186c250>] smp_apic_timer_interrupt+0x50/0x70 [ 962.951734] [<ffffffff81869994>] apic_timer_interrupt+0xd4/0xe0 [ 962.952755] <EOI> [ 962.952775] [<ffffffff81039130>] ? speculation_ctrl_update_tif+0x80/0x80 [ 962.954720] [<ffffffff81067af2>] ? native_safe_halt+0x12/0x20 [ 962.955703] [<ffffffff8103914e>] default_idle+0x1e/0xe0 [ 962.956652] [<ffffffff81039ff5>] arch_cpu_idle+0x15/0x20 [ 962.957571] [<ffffffff810cc03a>] default_idle_call+0x2a/0x40 [ 962.958491] [<ffffffff810cc3b3>] cpu_startup_entry+0x303/0x360 [ 962.959399] [<ffffffff81053e67>] start_secondary+0x177/0x1b0 [ 962.960305] Code: 8b 5c 24 40 75 46 f6 c2 02 74 05 f6 c2 30 75 3c 48 8b 43 58 44 89 5c 24 34 89 54 24 40 44 89 44 24 48 4c 89 4c 24 60 48 83 e0 fe <48> 8b 78 18 e8 4c 0b 03 00 41 89 c2 4c 8b 4c 24 60 44 8b 44 24 [ 962.963319] RIP [<ffffffff818288ab>] icmp6_send+0x1fb/0x970 [ 962.964291] RSP <ffff88013fd83d00> [ 962.965247] CR2: 0000000000000018 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1883681 Title: System freezes on specific kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1883681/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
