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BUG: KASAN: use-after-free in l2cap_chan_close+0x726/0xc80 net/bluetooth/l2cap_core.c:794
Read of size 1 at addr ffff88809d7c8020 by task kworker/0:2/45

CPU: 0 PID: 45 Comm: kworker/0:2 Not tainted 5.7.0-rc1-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+0x12d/0x187 lib/dump_stack.c:118
 print_address_description.constprop.8.cold.10+0x9/0x31d mm/kasan/report.c:382
 __kasan_report.cold.11+0x37/0x4e mm/kasan/report.c:511
 kasan_report+0x38/0x50 mm/kasan/common.c:625
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:143
 l2cap_chan_close+0x726/0xc80 net/bluetooth/l2cap_core.c:794
 do_enable_set+0x47e/0x8b0 net/bluetooth/6lowpan.c:1074
 process_one_work+0x893/0x1690 kernel/workqueue.c:2268
 worker_thread+0x85/0xb60 kernel/workqueue.c:2414
 kthread+0x354/0x420 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 2940:
 save_stack+0x21/0x50 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc.constprop.17+0xc7/0xd0 mm/kasan/common.c:495
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:509
 kmem_cache_alloc_trace+0x15b/0x780 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 l2cap_chan_create+0x41/0x360 net/bluetooth/l2cap_core.c:450
 chan_create+0xa/0xc0 net/bluetooth/6lowpan.c:640
 bt_6lowpan_listen net/bluetooth/6lowpan.c:959 [inline]
 do_enable_set+0x4af/0x8b0 net/bluetooth/6lowpan.c:1078
 process_one_work+0x893/0x1690 kernel/workqueue.c:2268
 worker_thread+0x85/0xb60 kernel/workqueue.c:2414
 kthread+0x354/0x420 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 2940:
 save_stack+0x21/0x50 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:456
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:465
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x108/0x2c0 mm/slab.c:3757
 l2cap_chan_destroy net/bluetooth/l2cap_core.c:488 [inline]
 kref_put include/linux/kref.h:65 [inline]
 l2cap_chan_put+0x15d/0x1d0 net/bluetooth/l2cap_core.c:502
 do_enable_set+0x48a/0x8b0 net/bluetooth/6lowpan.c:1075
 process_one_work+0x893/0x1690 kernel/workqueue.c:2268
 worker_thread+0x85/0xb60 kernel/workqueue.c:2414
 kthread+0x354/0x420 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff88809d7c8000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 32 bytes inside of
 2048-byte region [ffff88809d7c8000, ffff88809d7c8800)
The buggy address belongs to the page:
page:ffffea000275f200 refcount:1 mapcount:0 mapping:000000006a2a74c8 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea000238c508 ffffea000276fac8 ffff8880aa400e00
raw: 0000000000000000 ffff88809d7c8000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809d7c7f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809d7c7f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809d7c8000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff88809d7c8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809d7c8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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