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BUG: KASAN: slab-use-after-free in hci_conn_drop+0x34/0x2a0
Write of size 4 at addr ffff8881bae7c010 by task kworker/u11:1/5225

CPU: 0 UID: 0 PID: 5225 Comm: kworker/u11:1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: hci2 hci_cmd_sync_work
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_report+0xba/0x230
 kasan_report+0x117/0x150
 kasan_check_range+0x264/0x2c0
 hci_conn_drop+0x34/0x2a0
 hci_cmd_sync_work+0x262/0x400
 process_scheduled_works+0xaec/0x17a0
 worker_thread+0x89f/0xd90
 kthread+0x726/0x8b0
 ret_from_fork+0x51b/0xa40
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 5852:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x3d1/0x6e0
 __hci_conn_add+0x3c5/0x1b30
 le_conn_complete_evt+0x706/0x1430
 hci_le_conn_complete_evt+0x187/0x470
 hci_event_packet+0x7af/0x12c0
 hci_rx_work+0x3ee/0x1030
 process_scheduled_works+0xaec/0x17a0
 worker_thread+0x89f/0xd90
 kthread+0x726/0x8b0
 ret_from_fork+0x51b/0xa40
 ret_from_fork_asm+0x1a/0x30

Freed by task 5852:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x1be/0x650
 device_release+0x9e/0x1d0
 kobject_put+0x228/0x560
 hci_conn_del+0xc36/0x1230
 hci_disconn_complete_evt+0x64e/0x950
 hci_event_packet+0x805/0x12c0
 hci_rx_work+0x3ee/0x1030
 process_scheduled_works+0xaec/0x17a0
 worker_thread+0x89f/0xd90
 kthread+0x726/0x8b0
 ret_from_fork+0x51b/0xa40
 ret_from_fork_asm+0x1a/0x30

The buggy address belongs to the object at ffff8881bae7c000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 16 bytes inside of
 freed 8192-byte region [ffff8881bae7c000, ffff8881bae7e000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1bae78
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff888100042280 ffffea0000c80600 0000000000000005
raw: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff888100042280 ffffea0000c80600 0000000000000005
head: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000
head: 057ff00000000003 ffffea0006eb9e01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 8633, tgid 8632 (syz.7.553), ts 188213460831, free_ts 186039618005
 post_alloc_hook+0x231/0x280
 get_page_from_freelist+0x24dc/0x2580
 __alloc_frozen_pages_noprof+0x18d/0x380
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x86/0x3a0
 ___slab_alloc+0xd82/0x1760
 __slab_alloc+0x65/0x100
 __kmalloc_noprof+0x46c/0x7e0
 n_hdlc_alloc_buf+0x9f/0x280
 n_hdlc_tty_open+0x261/0x490
 tty_ldisc_open+0xa1/0x100
 tty_set_ldisc+0x373/0x560
 tty_ioctl+0xc37/0xde0
 __se_sys_ioctl+0xfc/0x170
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 8561 tgid 8559 stack trace:
 __free_frozen_pages+0xbb9/0xd10
 __put_partials+0x146/0x170
 __slab_free+0x294/0x320
 qlist_free_all+0x97/0x100
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 kmem_cache_alloc_node_noprof+0x427/0x6f0
 __alloc_skb+0x1d7/0x390
 tcp_stream_alloc_skb+0x3d/0x350
 tcp_sendmsg_locked+0x1af1/0x55b0
 tcp_sendmsg+0x2f/0x50
 __sock_sendmsg+0x19c/0x270
 sock_sendmsg+0x192/0x290
 splice_to_socket+0xae2/0x11f0
 direct_splice_actor+0x101/0x160
 splice_direct_to_actor+0x53a/0xc70

Memory state around the buggy address:
 ffff8881bae7bf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881bae7bf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881bae7c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8881bae7c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881bae7c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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