Observed on Samus when running chromeos-4.19.

2018-11-01T14:14:10.145821-07:00 WARNING kernel: [    3.873602] ------------[ cut here ]------------
2018-11-01T14:14:10.145882-07:00 WARNING kernel: [    3.876927] Bad or missing usercopy whitelist? Kernel memory exposure attempt detected from SLUB object 'task_struct' (offset 1856, size 8)!
2018-11-01T14:14:10.145884-07:00 WARNING kernel: [    3.889678] WARNING: CPU: 1 PID: 1 at /mnt/host/source/src/third_party/kernel/v4.19/mm/usercopy.c:83 usercopy_warn+0x95/0x9a
2018-11-01T14:14:10.145889-07:00 WARNING kernel: [    3.901117] Modules linked in:
2018-11-01T14:14:10.145890-07:00 WARNING kernel: [    3.903951] CPU: 1 PID: 1 Comm: init Tainted: G     U            4.19.0 #2
2018-11-01T14:14:10.145891-07:00 WARNING kernel: [    3.911051] Hardware name: GOOGLE Samus, BIOS Google_Samus.6300.276.0 08/17/2016
2018-11-01T14:14:10.145891-07:00 WARNING kernel: [    3.918208] RIP: 0010:usercopy_warn+0x95/0x9a
2018-11-01T14:14:10.145892-07:00 WARNING kernel: [    3.922546] Code: c6 04 25 29 d0 b1 8f 01 48 c7 c3 e1 2c 80 8f 48 0f 44 d8 48 c7 c7 63 2c 80 8f 31 c0 41 52 41 53 53 e8 3e f4 ea ff 48 83 c4 18 <0f> 0b 5b 5d c3 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 41 54 53 48
2018-11-01T14:14:10.145893-07:00 WARNING kernel: [    3.942142] RSP: 0018:ffffb66200013ce8 EFLAGS: 00010286
2018-11-01T14:14:10.145896-07:00 WARNING kernel: [    3.946786] RAX: 4f11cb71da580d00 RBX: ffffffff8f802ce1 RCX: ffffffff8fa47de0
2018-11-01T14:14:10.145897-07:00 WARNING kernel: [    3.954855] RDX: 0000000000000001 RSI: 0000000000000082 RDI: ffffffff8fa47db0
2018-11-01T14:14:10.145898-07:00 WARNING kernel: [    3.961997] RBP: ffffb66200013cf0 R08: 0000000000000000 R09: 0000000000000007
2018-11-01T14:14:10.145899-07:00 WARNING kernel: [    3.969168] R10: fffffffffffffd6c R11: ffffffff8eac2bf2 R12: ffffa23f2ce10748
2018-11-01T14:14:10.145900-07:00 WARNING kernel: [    3.976279] R13: ffffa23f2ce10000 R14: 0000000000000008 R15: 0000000000000001
2018-11-01T14:14:10.145900-07:00 WARNING kernel: [    3.983418] FS:  000079a6fd507800(0000) GS:ffffa23f2ea80000(0000) knlGS:0000000000000000
2018-11-01T14:14:10.145904-07:00 WARNING kernel: [    3.990766] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
2018-11-01T14:14:10.145905-07:00 WARNING kernel: [    3.996535] CR2: 000057daecdde908 CR3: 000000046aef6003 CR4: 00000000003606e0
2018-11-01T14:14:10.145905-07:00 WARNING kernel: [    4.003724] Call Trace:
2018-11-01T14:14:10.145906-07:00 WARNING kernel: [    4.006418]  __check_object_size+0xd2/0x1bb
2018-11-01T14:14:10.145907-07:00 WARNING kernel: [    4.010615]  do_signal+0x460/0x56b
2018-11-01T14:14:10.145908-07:00 WARNING kernel: [    4.014664]  prepare_exit_to_usermode+0x86/0xfd
2018-11-01T14:14:10.145909-07:00 WARNING kernel: [    4.018957]  syscall_return_slowpath+0x42/0x175
2018-11-01T14:14:10.145912-07:00 WARNING kernel: [    4.023379]  ? __se_sys_select+0x88/0xe6
2018-11-01T14:14:10.145913-07:00 WARNING kernel: [    4.027507]  ? ksys_read+0x71/0x9b
2018-11-01T14:14:10.145914-07:00 WARNING kernel: [    4.030595]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
2018-11-01T14:14:10.145914-07:00 WARNING kernel: [    4.036058] RIP: 0033:0x79a6fcf5f023
2018-11-01T14:14:10.145915-07:00 WARNING kernel: [    4.039194] Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d a9 b0 2b 00 00 75 13 49 89 ca b8 17 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 3b 51 01 00 48 89 04 24
2018-11-01T14:14:10.145916-07:00 WARNING kernel: [    4.057808] RSP: 002b:00007ffe033b4748 EFLAGS: 00000246 ORIG_RAX: 0000000000000017
2018-11-01T14:14:10.145920-07:00 WARNING kernel: [    4.066005] RAX: fffffffffffffffc RBX: 00007ffe033b47a0 RCX: 000079a6fcf5f023
2018-11-01T14:14:10.145920-07:00 WARNING kernel: [    4.073145] RDX: 00007ffe033b4820 RSI: 00007ffe033b48a0 RDI: 0000000000000008
2018-11-01T14:14:10.145921-07:00 WARNING kernel: [    4.080349] RBP: 00007ffe033b4950 R08: 0000000000000000 R09: 0000000000001228
2018-11-01T14:14:10.145922-07:00 WARNING kernel: [    4.087591] R10: 00007ffe033b47a0 R11: 0000000000000246 R12: 00007ffe033b47a0
2018-11-01T14:14:10.145923-07:00 WARNING kernel: [    4.094771] R13: 00007ffe033b4820 R14: 00007ffe033b479f R15: 00007ffe033b4760
2018-11-01T14:14:10.145924-07:00 WARNING kernel: [    4.101913] ---[ end trace 0201c49f82d28794 ]---