IPVS: Unknown mcast interface: netpci0
==================================================================
BUG: KASAN: use-after-free in pppol2tp_session_close+0xc4/0xd0 net/l2tp/l2tp_ppp.c:436
Read of size 8 at addr ffff888050a88fe0 by task kworker/u4:2/33

CPU: 1 PID: 33 Comm: kworker/u4:2 Not tainted 4.14.172-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: l2tp l2tp_tunnel_del_work
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x13e/0x194 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1e2 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2ae mm/kasan/report.c:393
device sit1 entered promiscuous mode
 pppol2tp_session_close+0xc4/0xd0 net/l2tp/l2tp_ppp.c:436
 l2tp_tunnel_closeall+0x234/0x370 net/l2tp/l2tp_core.c:1345
 l2tp_tunnel_del_work+0x61/0x400 net/l2tp/l2tp_core.c:1385
 process_one_work+0x813/0x1540 kernel/workqueue.c:2114
 worker_thread+0x5d1/0x1070 kernel/workqueue.c:2248
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 14933:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529
 kmem_cache_alloc_trace+0x14d/0x7b0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 snd_seq_oss_open+0x50/0x8a0 sound/core/seq/oss/seq_oss_init.c:190
 odev_open+0x62/0x80 sound/core/seq/oss/seq_oss.c:138
 soundcore_open+0x3ee/0x5a0 sound/sound_core.c:640
 chrdev_open+0x1fc/0x540 fs/char_dev.c:423
 do_dentry_open+0x732/0xe90 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:891
 do_last fs/namei.c:3428 [inline]
 path_openat+0x8ca/0x3c50 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x29d/0x3f0 fs/open.c:1084
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 14933:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcb/0x260 mm/slab.c:3815
 port_delete+0xd7/0x190 sound/core/seq/seq_ports.c:273
 snd_seq_delete_port+0x23b/0x2f0 sound/core/seq/seq_ports.c:303
 snd_seq_ioctl_delete_port+0xa5/0x170 sound/core/seq/seq_clientmgr.c:1330
 snd_seq_kernel_client_ctl+0xcb/0x110 sound/core/seq/seq_clientmgr.c:2360
 snd_seq_event_port_detach+0x91/0xc0 sound/core/seq/seq_ports.c:708
 delete_port+0x6f/0xb0 sound/core/seq/oss/seq_oss_init.c:354
 snd_seq_oss_release+0xe2/0x130 sound/core/seq/oss/seq_oss_init.c:433
 odev_release+0x4f/0x70 sound/core/seq/oss/seq_oss.c:153
 __fput+0x25f/0x790 fs/file_table.c:210
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1d6/0x220 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff888050a88c00
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 992 bytes inside of
 2048-byte region [ffff888050a88c00, ffff888050a89400)
The buggy address belongs to the page:
page:ffffea000142a200 count:1 mapcount:0 mapping:ffff888050a88380 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff888050a88380 0000000000000000 0000000100000003
raw: ffffea00021ef6a0 ffffea00020bb8a0 ffff88812fe56c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888050a88e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888050a88f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888050a88f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff888050a89000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888050a89080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
IPVS: Unknown mcast interface: netpci0