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BUG: KASAN: slab-use-after-free in hci_conn_drop+0x34/0x2b0
Write of size 4 at addr ffff8881b2390010 by task kworker/u11:4/5856

CPU: 0 UID: 0 PID: 5856 Comm: kworker/u11:4 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: hci1 hci_cmd_sync_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 print_report+0xca/0x240
 kasan_report+0x118/0x150
 kasan_check_range+0x2b0/0x2c0
 hci_conn_drop+0x34/0x2b0
 hci_cmd_sync_work+0x262/0x400
 process_scheduled_works+0xad1/0x1770
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x599/0xb30
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 5225:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x3e2/0x700
 __hci_conn_add+0x3c5/0x1b30
 le_conn_complete_evt+0x6f6/0x1420
 hci_le_conn_complete_evt+0x187/0x480
 hci_event_packet+0x78f/0x1260
 hci_rx_work+0x3ee/0x1060
 process_scheduled_works+0xad1/0x1770
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x599/0xb30
 ret_from_fork_asm+0x1a/0x30

Freed by task 5225:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x1c0/0x660
 device_release+0x9e/0x1d0
 kobject_put+0x228/0x570
 hci_conn_del+0xc36/0x1240
 hci_disconn_complete_evt+0x64e/0x950
 hci_event_packet+0x7e3/0x1260
 hci_rx_work+0x3ee/0x1060
 process_scheduled_works+0xad1/0x1770
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x599/0xb30
 ret_from_fork_asm+0x1a/0x30

The buggy address belongs to the object at ffff8881b2390000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 16 bytes inside of
 freed 8192-byte region [ffff8881b2390000, ffff8881b2392000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1b2390
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 ffffea0006be3400 0000000000000005
raw: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff888100042280 ffffea0006be3400 0000000000000005
head: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000
head: 057ff00000000003 ffffea0006c8e401 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 0x528c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NORETRY|__GFP_COMP), pid 14541, tgid 14541 (syz-executor), ts 383076849697, free_ts 383061285610
 post_alloc_hook+0x23d/0x2a0
 get_page_from_freelist+0x22f6/0x23d0
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x86/0x3b0
 ___slab_alloc+0xf2b/0x1960
 __slab_alloc+0x65/0x100
 __kvmalloc_node_noprof+0x6b6/0x920
 pfifo_fast_init+0x242/0x6c0
 qdisc_create_dflt+0x13b/0x4c0
 mq_init+0x2dc/0x660
 qdisc_create_dflt+0x13b/0x4c0
 dev_activate+0x1ce/0x1150
 __dev_open+0x647/0x800
 __dev_change_flags+0x1f7/0x680
 netif_change_flags+0x88/0x1a0
page last free pid 5771 tgid 5771 stack trace:
 __free_frozen_pages+0xb99/0xd10
 __put_partials+0x146/0x170
 put_cpu_partial+0x1f2/0x2d0
 __slab_free+0x288/0x2a0
 qlist_free_all+0x97/0x100
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 kmem_cache_alloc_node_noprof+0x43c/0x720
 __alloc_skb+0x255/0x430
 tcp_stream_alloc_skb+0x3d/0x350
 tcp_sendmsg_locked+0x1ab8/0x5520
 tcp_sendmsg+0x2f/0x50
 __sock_sendmsg+0x19c/0x270
 sock_write_iter+0x279/0x360
 vfs_write+0x5c9/0xb30
 ksys_write+0x145/0x250

Memory state around the buggy address:
 ffff8881b238ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881b238ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881b2390000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8881b2390080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881b2390100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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