cgroup: fork rejected by pids controller in /syz3
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BUG: KASAN: use-after-free in __list_del_entry_valid+0xf1/0x100 lib/list_debug.c:51
Read of size 8 at addr ffff8881b4cd0b70 by task kworker/1:0/17

CPU: 1 PID: 17 Comm: kworker/1:0 Not tainted 4.20.0-rc6-next-20181210+ #164
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_power_efficient neigh_periodic_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x244/0x39d lib/dump_stack.c:113
 print_address_description.cold.4+0x9/0x1ff mm/kasan/report.c:187
 kasan_report.cold.5+0x1b/0x39 mm/kasan/report.c:317
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
 __list_del_entry_valid+0xf1/0x100 lib/list_debug.c:51
 __list_del_entry include/linux/list.h:117 [inline]
 list_del_init include/linux/list.h:159 [inline]
 neigh_mark_dead+0x13b/0x410 net/core/neighbour.c:125
 neigh_periodic_work+0x89a/0xc30 net/core/neighbour.c:905
 process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
 kthread+0x35a/0x440 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 5957:
 save_stack+0x43/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 kasan_kmalloc+0xcb/0xd0 mm/kasan/common.c:482
 kmem_cache_alloc_trace+0x154/0x740 mm/slab.c:3607
 kmalloc include/linux/slab.h:545 [inline]
 syslog_print kernel/printk/printk.c:1314 [inline]
 do_syslog+0xb9b/0x1690 kernel/printk/printk.c:1482
 kmsg_read+0x8f/0xc0 fs/proc/kmsg.c:40
 proc_reg_read+0x2a3/0x3d0 fs/proc/inode.c:227
 __vfs_read+0x117/0xa80 fs/read_write.c:416
 vfs_read+0x17f/0x3e0 fs/read_write.c:452
 ksys_read+0x101/0x260 fs/read_write.c:578
 __do_sys_read fs/read_write.c:588 [inline]
 __se_sys_read fs/read_write.c:586 [inline]
 __x64_sys_read+0x73/0xb0 fs/read_write.c:586
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 5957:
 save_stack+0x43/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:444
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:452
 __cache_free mm/slab.c:3485 [inline]
 kfree+0xcf/0x230 mm/slab.c:3804
 syslog_print kernel/printk/printk.c:1365 [inline]
 do_syslog+0x147b/0x1690 kernel/printk/printk.c:1482
 kmsg_read+0x8f/0xc0 fs/proc/kmsg.c:40
 proc_reg_read+0x2a3/0x3d0 fs/proc/inode.c:227
 __vfs_read+0x117/0xa80 fs/read_write.c:416
 vfs_read+0x17f/0x3e0 fs/read_write.c:452
 ksys_read+0x101/0x260 fs/read_write.c:578
 __do_sys_read fs/read_write.c:588 [inline]
 __se_sys_read fs/read_write.c:586 [inline]
 __x64_sys_read+0x73/0xb0 fs/read_write.c:586
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881b4cd0900
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 624 bytes inside of
 1024-byte region [ffff8881b4cd0900, ffff8881b4cd0d00)
The buggy address belongs to the page:
page:ffffea0006d33400 count:1 mapcount:0 mapping:ffff8881da800ac0 index:0xffff8881b4cd0000 compound_mapcount: 0
flags: 0x2fffc0000010200(slab|head)
raw: 02fffc0000010200 ffffea00075d1208 ffffea00075df108 ffff8881da800ac0
raw: ffff8881b4cd0000 ffff8881b4cd0000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881b4cd0a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881b4cd0a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881b4cd0b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                             ^
 ffff8881b4cd0b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881b4cd0c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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