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BUG: KASAN: use-after-free in l2cap_chan_close+0x46/0xae0 net/bluetooth/l2cap_core.c:790
Read of size 8 at addr ffff88808ec44000 by task kworker/0:4/2721

CPU: 0 PID: 2721 Comm: kworker/0:4 Not tainted 5.7.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events do_enable_set
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1e9/0x30e lib/dump_stack.c:118
 print_address_description+0x74/0x5c0 mm/kasan/report.c:382
 __kasan_report+0x103/0x1a0 mm/kasan/report.c:511
 kasan_report+0x4d/0x80 mm/kasan/common.c:625

Allocated by task 2721:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc+0x114/0x160 mm/kasan/common.c:495
 kmem_cache_alloc_trace+0x234/0x300 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 l2cap_chan_create+0x4c/0x320 net/bluetooth/l2cap_core.c:450
 chan_create net/bluetooth/6lowpan.c:640 [inline]
 bt_6lowpan_listen net/bluetooth/6lowpan.c:959 [inline]
 do_enable_set+0x673/0x8d0 net/bluetooth/6lowpan.c:1078
 process_one_work+0x76e/0xfd0 kernel/workqueue.c:2268
 worker_thread+0xa7f/0x1450 kernel/workqueue.c:2414
 kthread+0x353/0x380 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

Freed by task 3031:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0x125/0x190 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x220 mm/slab.c:3757
 do_enable_set+0x63a/0x8d0 net/bluetooth/6lowpan.c:1075
 process_one_work+0x76e/0xfd0 kernel/workqueue.c:2268
 worker_thread+0xa7f/0x1450 kernel/workqueue.c:2414
 kthread+0x353/0x380 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

The buggy address belongs to the object at ffff88808ec44000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 0 bytes inside of
 2048-byte region [ffff88808ec44000, ffff88808ec44800)
The buggy address belongs to the page:
page:ffffea00023b1100 refcount:1 mapcount:0 mapping:000000007d6d3db6 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002a2e448 ffffea00024ef448 ffff8880aa400e00
raw: 0000000000000000 ffff88808ec44000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808ec43f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88808ec43f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88808ec44000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88808ec44080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808ec44100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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