syzbot

audit: type=1400 audit(1601306915.323:8): avc:  denied  { execmem } for  pid=6384 comm="syz-executor465" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
IPVS: ftp: loaded support on port[0] = 21
==================================================================
BUG: KASAN: use-after-free in hci_chan_del+0x131/0x180 net/bluetooth/hci_conn.c:1547
Read of size 8 at addr ffff8880926c63d8 by task syz-executor465/6385

CPU: 0 PID: 6385 Comm: syz-executor465 Not tainted 4.14.198-syzkaller #0
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+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
 hci_chan_del+0x131/0x180 net/bluetooth/hci_conn.c:1547
 l2cap_conn_del+0x417/0x670 net/bluetooth/l2cap_core.c:1736
 l2cap_disconn_cfm net/bluetooth/l2cap_core.c:7435 [inline]
 l2cap_disconn_cfm+0x6b/0x80 net/bluetooth/l2cap_core.c:7428
 hci_disconn_cfm include/net/bluetooth/hci_core.h:1226 [inline]
 hci_conn_hash_flush+0x114/0x220 net/bluetooth/hci_conn.c:1376
 hci_dev_do_close+0x542/0xc50 net/bluetooth/hci_core.c:1620
 hci_unregister_dev+0x170/0x7a0 net/bluetooth/hci_core.c:3191
 vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:354
 __fput+0x25f/0x7a0 fs/file_table.c:210
 task_work_run+0x11f/0x190 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xa08/0x27f0 kernel/exit.c:865
 do_group_exit+0x100/0x2e0 kernel/exit.c:962
 SYSC_exit_group kernel/exit.c:973 [inline]
 SyS_exit_group+0x19/0x20 kernel/exit.c:971
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4450c8
RSP: 002b:00007ffea48c61c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004450c8
RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001
RBP: 00000000004cce50 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006e0200 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 6388:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x131/0x3d0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 hci_chan_create+0x7c/0x300 net/bluetooth/hci_conn.c:1532
 l2cap_conn_add.part.0+0x18/0xc20 net/bluetooth/l2cap_core.c:7056
 l2cap_conn_add net/bluetooth/l2cap_core.c:7415 [inline]
 l2cap_connect_cfm+0x1d2/0xce0 net/bluetooth/l2cap_core.c:7373
 hci_connect_cfm include/net/bluetooth/hci_core.h:1211 [inline]
 hci_le_conn_complete_evt net/bluetooth/hci_event.c:4609 [inline]
 hci_le_meta_evt+0x3288/0x3fc0 net/bluetooth/hci_event.c:5168
 hci_event_packet+0x19eb/0x7d1d net/bluetooth/hci_event.c:5423
 hci_rx_work+0x3e6/0x970 net/bluetooth/hci_core.c:4244
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Freed by task 1200:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 hci_disconn_loglink_complete_evt net/bluetooth/hci_event.c:4440 [inline]
 hci_event_packet+0xee6/0x7d1d net/bluetooth/hci_event.c:5444
 hci_rx_work+0x3e6/0x970 net/bluetooth/hci_core.c:4244
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff8880926c63c0
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 24 bytes inside of
 128-byte region [ffff8880926c63c0, ffff8880926c6440)
The buggy address belongs to the page:
page:ffffea000249b180 count:1 mapcount:0 mapping:ffff8880926c6000 index:0xffff8880926c6780
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880926c6000 ffff8880926c6780 0000000100000009
raw: ffffea0002692a20 ffffea0002376320 ffff88812fe50640 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880926c6280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880926c6300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880926c6380: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                    ^
 ffff8880926c6400: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880926c6480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================