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BUG: KASAN: slab-use-after-free in hci_conn_drop+0x34/0x2a0
Write of size 4 at addr ffff888102b78010 by task kworker/u11:1/15771

CPU: 0 UID: 0 PID: 15771 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+0xb6e/0x18c0
 worker_thread+0xa53/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 15771:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x31c/0x660
 __hci_conn_add+0x3c4/0x1e00
 le_conn_complete_evt+0x706/0x1430
 hci_le_enh_conn_complete_evt+0x189/0x490
 hci_event_packet+0x7af/0x12c0
 hci_rx_work+0x3ee/0x1030
 process_scheduled_works+0xb6e/0x18c0
 worker_thread+0xa53/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30

Freed by task 5814:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x1c1/0x630
 device_release+0xc4/0x1f0
 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+0xb6e/0x18c0
 worker_thread+0xa53/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30

The buggy address belongs to the object at ffff888102b78000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 16 bytes inside of
 freed 8192-byte region [ffff888102b78000, ffff888102b7a000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x102b78
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000040 ffff888100042280 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000
head: 017ff00000000040 ffff888100042280 dead000000000100 dead000000000122
head: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000
head: 017ff00000000003 ffffea00040ade01 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 0xd28c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5555, tgid 5555 (dhcpcd), ts 148569401140, free_ts 148512239631
 post_alloc_hook+0x231/0x280
 get_page_from_freelist+0x24dc/0x2580
 __alloc_frozen_pages_noprof+0x18d/0x380
 allocate_slab+0x77/0x660
 refill_objects+0x331/0x3c0
 __pcs_replace_empty_main+0x2e6/0x730
 __kmalloc_node_track_caller_noprof+0x572/0x7b0
 __alloc_skb+0x2c1/0x7d0
 netlink_dump+0x190/0xe80
 netlink_recvmsg+0x690/0xa50
 sock_recvmsg+0x172/0x1b0
 ____sys_recvmsg+0x1e6/0x4a0
 ___sys_recvmsg+0x215/0x590
 __x64_sys_recvmsg+0x1ba/0x2a0
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5808 tgid 5808 stack trace:
 register_dummy_stack+0x98/0x100
 init_page_owner+0x2e/0x600
 page_ext_init+0x500/0x540
 mm_core_init+0x51/0x70

Memory state around the buggy address:
 ffff888102b77f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888102b77f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888102b78000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888102b78080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888102b78100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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