==================================================================
BUG: KASAN: use-after-free in worker_thread+0x15bb/0x1990 kernel/workqueue.c:2244
Read of size 8 at addr ffff8801c3c684e0 by task kworker/u4:0/5

CPU: 0 PID: 5 Comm: kworker/u4:0 Not tainted 4.14.0+ #125
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 worker_thread+0x15bb/0x1990 kernel/workqueue.c:2244
 kthread+0x37a/0x440 kernel/kthread.c:238
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:437

Allocated by task 12867:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3562
 kmem_cache_zalloc include/linux/slab.h:657 [inline]
 kcm_attach net/kcm/kcmsock.c:1394 [inline]
 kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
 kcm_ioctl+0x2d1/0x1610 net/kcm/kcmsock.c:1695
 sock_do_ioctl+0x65/0xb0 net/socket.c:961
 sock_ioctl+0x2c2/0x440 net/socket.c:1058
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x1f/0x96

Freed by task 5:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3504 [inline]
 kmem_cache_free+0x77/0x280 mm/slab.c:3764
 unreserve_psock+0x5a1/0x780 net/kcm/kcmsock.c:547
 kcm_write_msgs+0xbae/0x1b80 net/kcm/kcmsock.c:590
 kcm_tx_work+0x2e/0x190 net/kcm/kcmsock.c:731
 process_one_work+0xbfd/0x1be0 kernel/workqueue.c:2112
 worker_thread+0x223/0x1990 kernel/workqueue.c:2246
 kthread+0x37a/0x440 kernel/kthread.c:238
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:437

The buggy address belongs to the object at ffff8801c3c68400
 which belongs to the cache kcm_psock_cache of size 576
The buggy address is located 224 bytes inside of
 576-byte region [ffff8801c3c68400, ffff8801c3c68640)
The buggy address belongs to the page:
page:ffffea00070f1a00 count:1 mapcount:0 mapping:ffff8801c3c68140 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801c3c68140 0000000000000000 000000010000000b
raw: ffff8801d2b25250 ffff8801d2b25250 ffff8801d2493c00 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c3c68380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801c3c68400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801c3c68480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff8801c3c68500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c3c68580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================