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BUG: KASAN: use-after-free in hci_chan_del+0x1c5/0x200 net/bluetooth/hci_conn.c:1769
Read of size 8 at addr ffff8880126f8d18 by task syz-executor.2/16144

CPU: 0 PID: 16144 Comm: syz-executor.2 Not tainted 5.12.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
 __kasan_report mm/kasan/report.c:399 [inline]
 kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
 hci_chan_del+0x1c5/0x200 net/bluetooth/hci_conn.c:1769
 l2cap_conn_del+0x478/0x7b0 net/bluetooth/l2cap_core.c:1906
 l2cap_disconn_cfm net/bluetooth/l2cap_core.c:8168 [inline]
 l2cap_disconn_cfm+0x98/0xd0 net/bluetooth/l2cap_core.c:8161
 hci_disconn_cfm include/net/bluetooth/hci_core.h:1486 [inline]
 hci_conn_hash_flush+0x127/0x260 net/bluetooth/hci_conn.c:1598
 hci_dev_do_close+0x569/0x1110 net/bluetooth/hci_core.c:1778
 hci_unregister_dev+0x263/0x1130 net/bluetooth/hci_core.c:3989
 vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:340
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:140
 exit_task_work include/linux/task_work.h:30 [inline]
 do_exit+0xbfc/0x2a60 kernel/exit.c:825
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x47f/0x2150 kernel/signal.c:2781
 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:789
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x148/0x250 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
Code: Unable to access opcode bytes at RIP 0x46642f.
RSP: 002b:00007f6e90d46218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000056bf68 RCX: 0000000000466459
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000056bf68
RBP: 000000000056bf60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf6c
R13: 00007ffe58413f3f R14: 00007f6e90d46300 R15: 0000000000022000

Allocated by task 4836:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:427 [inline]
 ____kasan_kmalloc mm/kasan/common.c:506 [inline]
 ____kasan_kmalloc mm/kasan/common.c:465 [inline]
 __kasan_kmalloc+0x99/0xc0 mm/kasan/common.c:515
 kmalloc include/linux/slab.h:554 [inline]
 kernfs_get_open_node fs/kernfs/file.c:552 [inline]
 kernfs_fop_open+0x957/0xd40 fs/kernfs/file.c:698
 do_dentry_open+0x4b9/0x11b0 fs/open.c:826
 do_open fs/namei.c:3367 [inline]
 path_openat+0x1c0e/0x27e0 fs/namei.c:3500
 do_filp_open+0x190/0x3d0 fs/namei.c:3527
 do_sys_openat2+0x16d/0x420 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_open fs/open.c:1211 [inline]
 __se_sys_open fs/open.c:1207 [inline]
 __x64_sys_open+0x119/0x1c0 fs/open.c:1207
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 4836:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
 ____kasan_slab_free mm/kasan/common.c:360 [inline]
 ____kasan_slab_free mm/kasan/common.c:325 [inline]
 __kasan_slab_free+0xf5/0x130 mm/kasan/common.c:367
 kasan_slab_free include/linux/kasan.h:199 [inline]
 slab_free_hook mm/slub.c:1562 [inline]
 slab_free_freelist_hook+0x92/0x210 mm/slub.c:1600
 slab_free mm/slub.c:3161 [inline]
 kfree+0xe5/0x7f0 mm/slub.c:4213
 kernfs_fop_release+0xe3/0x190 fs/kernfs/file.c:760
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff8880126f8d00
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 24 bytes inside of
 128-byte region [ffff8880126f8d00, ffff8880126f8d80)
The buggy address belongs to the page:
page:ffffea000049be00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x126f8
flags: 0xfff00000000200(slab)
raw: 00fff00000000200 ffffea00008f86c0 0000000500000002 ffff8880104418c0
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880126f8c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880126f8c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880126f8d00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff8880126f8d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880126f8e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc
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