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BUG: KASAN: use-after-free in l2cap_chan_close+0x58b/0x820 net/bluetooth/l2cap_core.c:727
Read of size 1 at addr ffff8880a47d71a0 by task kworker/0:3/6151

CPU: 0 PID: 6151 Comm: kworker/0:3 Not tainted 4.19.137-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+0x1fc/0x2fe lib/dump_stack.c:118
 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1c7 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load1_noabort+0x88/0x90 mm/kasan/report.c:430
 l2cap_chan_close+0x58b/0x820 net/bluetooth/l2cap_core.c:727
 do_enable_set+0x4e3/0x975 net/bluetooth/6lowpan.c:1086
 process_one_work+0x864/0x1570 kernel/workqueue.c:2155
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
 kthread+0x30b/0x410 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 2763:
 kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
 kmalloc include/linux/slab.h:515 [inline]
 kzalloc include/linux/slab.h:709 [inline]
 l2cap_chan_create+0x40/0x380 net/bluetooth/l2cap_core.c:441
 chan_create net/bluetooth/6lowpan.c:652 [inline]
 bt_6lowpan_listen net/bluetooth/6lowpan.c:971 [inline]
 do_enable_set+0x525/0x975 net/bluetooth/6lowpan.c:1090
 process_one_work+0x864/0x1570 kernel/workqueue.c:2155
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
 kthread+0x30b/0x410 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Freed by task 2763:
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcc/0x210 mm/slab.c:3822
 l2cap_chan_destroy net/bluetooth/l2cap_core.c:479 [inline]
 kref_put include/linux/kref.h:70 [inline]
 l2cap_chan_put+0x16b/0x1c0 net/bluetooth/l2cap_core.c:493
 do_enable_set+0x4ef/0x975 net/bluetooth/6lowpan.c:1087
 process_one_work+0x864/0x1570 kernel/workqueue.c:2155
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
 kthread+0x30b/0x410 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

The buggy address belongs to the object at ffff8880a47d7180
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 32 bytes inside of
 2048-byte region [ffff8880a47d7180, ffff8880a47d7980)
The buggy address belongs to the page:
page:ffffea000291f580 count:1 mapcount:0 mapping:ffff88812c39cc40 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffffea0002903f08 ffffea000290ab88 ffff88812c39cc40
raw: 0000000000000000 ffff8880a47d6080 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a47d7080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a47d7100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a47d7180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff8880a47d7200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a47d7280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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