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BUG: KASAN: use-after-free in hci_conn_del+0x64e/0x6a0 net/bluetooth/hci_conn.c:630
Write of size 8 at addr ffff88809418a938 by task syz-executor.3/9868

CPU: 1 PID: 9868 Comm: syz-executor.3 Not tainted 5.8.0-rc7-next-20200731-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 hci_conn_del+0x64e/0x6a0 net/bluetooth/hci_conn.c:630
 hci_conn_hash_flush+0x189/0x220 net/bluetooth/hci_conn.c:1558
 hci_dev_do_close+0x5c6/0x1080 net/bluetooth/hci_core.c:1770
 hci_unregister_dev+0x1bd/0xe30 net/bluetooth/hci_core.c:3790
 vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:340
 __fput+0x285/0x920 fs/file_table.c:281
 task_work_run+0xdd/0x190 kernel/task_work.c:135
 exit_task_work include/linux/task_work.h:25 [inline]
 do_exit+0xb7d/0x29f0 kernel/exit.c:806
 do_group_exit+0x125/0x310 kernel/exit.c:903
 __do_sys_exit_group kernel/exit.c:914 [inline]
 __se_sys_exit_group kernel/exit.c:912 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:912
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45ccd9
Code: Bad RIP value.
RSP: 002b:00007fffce703448 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045ccd9
RDX: 0000000000416731 RSI: 0000000000ca85f0 RDI: 0000000000000043
RBP: 00000000004c2963 R08: 000000000000000b R09: 0000000000000000
R10: 0000000001a5a940 R11: 0000000000000246 R12: 000000000000000a
R13: 00007fffce703590 R14: 000000000004a418 R15: 00007fffce7035a0

Allocated by task 8136:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0xae/0x550 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1084 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:501 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:558 [inline]
 nsim_dev_trap_report_work+0x2b2/0xbe0 drivers/net/netdevsim/dev.c:599
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Freed by task 8136:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422
 __cache_free mm/slab.c:3418 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3756
 skb_free_head net/core/skbuff.c:590 [inline]
 skb_release_data+0x6d9/0x910 net/core/skbuff.c:610
 skb_release_all net/core/skbuff.c:664 [inline]
 __kfree_skb net/core/skbuff.c:678 [inline]
 consume_skb net/core/skbuff.c:837 [inline]
 consume_skb+0xc2/0x160 net/core/skbuff.c:831
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:574 [inline]
 nsim_dev_trap_report_work+0x889/0xbe0 drivers/net/netdevsim/dev.c:599
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

The buggy address belongs to the object at ffff88809418a000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 2360 bytes inside of
 4096-byte region [ffff88809418a000, ffff88809418b000)
The buggy address belongs to the page:
page:000000001fb2753a refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x9418a
head:000000001fb2753a order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0002492688 ffffea0002231d88 ffff8880aa000900
raw: 0000000000000000 ffff88809418a000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809418a800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809418a880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809418a900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff88809418a980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809418aa00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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