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BUG: KASAN: use-after-free in __lock_acquire+0x2c57/0x3f20 kernel/locking/lockdep.c:3369
Read of size 8 at addr ffff88808f7c7660 by task kworker/1:3/8000

CPU: 1 PID: 8000 Comm: kworker/1:3 Not tainted 4.14.236-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
 __lock_acquire+0x2c57/0x3f20 kernel/locking/lockdep.c:3369
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:176
 spin_lock_bh include/linux/spinlock.h:322 [inline]
 lock_sock_nested+0x39/0x100 net/core/sock.c:2788
 l2cap_sock_teardown_cb+0x93/0x650 net/bluetooth/l2cap_sock.c:1349
 l2cap_chan_del+0xaf/0x950 net/bluetooth/l2cap_core.c:603
 l2cap_chan_close+0x103/0x870 net/bluetooth/l2cap_core.c:761
 l2cap_chan_timeout+0x143/0x2a0 net/bluetooth/l2cap_core.c:430
 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

Allocated by task 10638:
 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]
 l2cap_chan_create+0x3e/0x580 net/bluetooth/l2cap_core.c:444
 l2cap_sock_alloc.constprop.0+0x16c/0x210 net/bluetooth/l2cap_sock.c:1641
 l2cap_sock_create+0xf0/0x1a0 net/bluetooth/l2cap_sock.c:1672
 bt_sock_create+0x13b/0x280 net/bluetooth/af_bluetooth.c:130
 __sock_create+0x303/0x620 net/socket.c:1275
 sock_create net/socket.c:1315 [inline]
 SYSC_socket net/socket.c:1345 [inline]
 SyS_socket+0xd1/0x1b0 net/socket.c:1325
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 10638:
 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
 l2cap_chan_destroy net/bluetooth/l2cap_core.c:484 [inline]
 kref_put include/linux/kref.h:70 [inline]
 l2cap_chan_put+0x1c2/0x250 net/bluetooth/l2cap_core.c:498
 l2cap_sock_release+0x1e2/0x280 net/bluetooth/l2cap_sock.c:1221
 __sock_release+0xcd/0x2b0 net/socket.c:602
 sock_close+0x15/0x20 net/socket.c:1139
 __fput+0x25f/0x7a0 fs/file_table.c:210
 task_work_run+0x11f/0x190 kernel/task_work.c:113
 get_signal+0x18a3/0x1ca0 kernel/signal.c:2234
 do_signal+0x7c/0x1550 arch/x86/kernel/signal.c:792
 exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160
 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+0x46/0xbb

The buggy address belongs to the object at ffff88808f7c75c0
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 160 bytes inside of
 2048-byte region [ffff88808f7c75c0, ffff88808f7c7dc0)
The buggy address belongs to the page:
page:ffffea00023df180 count:1 mapcount:0 mapping:ffff88808f7c64c0 index:0x0 compound_mapcount: 0
flags: 0xfff00000008100(slab|head)
raw: 00fff00000008100 ffff88808f7c64c0 0000000000000000 0000000100000003
raw: ffffea0002682ca0 ffffea00026a9ca0 ffff88813fe80c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808f7c7500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88808f7c7580: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff88808f7c7600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff88808f7c7680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808f7c7700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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