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BUG: KASAN: use-after-free in hci_chan_del+0x14f/0x190 net/bluetooth/hci_conn.c:1707
Read of size 8 at addr ffff8880a7037518 by task syz-executor.0/6876

CPU: 0 PID: 6876 Comm: syz-executor.0 Not tainted 5.8.0-rc7-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/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 hci_chan_del+0x14f/0x190 net/bluetooth/hci_conn.c:1707
 l2cap_conn_del+0x61b/0x9e0 net/bluetooth/l2cap_core.c:1900
 l2cap_disconn_cfm net/bluetooth/l2cap_core.c:8159 [inline]
 l2cap_disconn_cfm+0x85/0xa0 net/bluetooth/l2cap_core.c:8152
 hci_disconn_cfm include/net/bluetooth/hci_core.h:1355 [inline]
 hci_conn_hash_flush+0x114/0x220 net/bluetooth/hci_conn.c:1536
 hci_dev_do_close+0x5c6/0x1080 net/bluetooth/hci_core.c:1761
 hci_unregister_dev+0x1a3/0xe20 net/bluetooth/hci_core.c:3606
 vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:340
 __fput+0x33c/0x880 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+0xb72/0x2a40 kernel/exit.c:805
 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+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cce9
Code: Bad RIP value.
RSP: 002b:00007fff7af90ab8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045cce9
RDX: 0000000000416741 RSI: 0000000000ca85f0 RDI: 0000000000000043
RBP: 00000000004c2983 R08: 000000000000000b R09: 0000000000000000
R10: 00000000011fd940 R11: 0000000000000246 R12: 0000000000000003
R13: 00007fff7af90c00 R14: 00000000001117c0 R15: 00007fff7af90c10

Allocated by task 3903:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 kmem_cache_alloc_trace+0x14f/0x2d0 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kernfs_get_open_node fs/kernfs/file.c:571 [inline]
 kernfs_fop_open+0x957/0xd40 fs/kernfs/file.c:717
 do_dentry_open+0x501/0x1290 fs/open.c:828
 do_open fs/namei.c:3243 [inline]
 path_openat+0x1bb9/0x2750 fs/namei.c:3360
 do_filp_open+0x17e/0x3c0 fs/namei.c:3387
 do_sys_openat2+0x16f/0x3b0 fs/open.c:1179
 do_sys_open fs/open.c:1195 [inline]
 ksys_open include/linux/syscalls.h:1388 [inline]
 __do_sys_open fs/open.c:1201 [inline]
 __se_sys_open fs/open.c:1199 [inline]
 __x64_sys_open+0x119/0x1c0 fs/open.c:1199
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 3903:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3757
 kernfs_fop_release+0xe3/0x190 fs/kernfs/file.c:779
 __fput+0x33c/0x880 fs/file_table.c:281
 task_work_run+0xdd/0x190 kernel/task_work.c:135
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:239 [inline]
 __prepare_exit_to_usermode+0x1e9/0x1f0 arch/x86/entry/common.c:269
 do_syscall_64+0x6c/0xe0 arch/x86/entry/common.c:393
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8880a7037500
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 24 bytes inside of
 128-byte region [ffff8880a7037500, ffff8880a7037580)
The buggy address belongs to the page:
page:ffffea00029c0dc0 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880a7037000
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00029d8188 ffffea00027df648 ffff8880aa000700
raw: ffff8880a7037000 ffff8880a7037000 0000000100000008 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a7037400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a7037480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a7037500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff8880a7037580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a7037600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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