==================================================================
BUG: KASAN: slab-use-after-free in l2cap_sock_new_connection_cb+0x208/0x2f0
Read of size 8 at addr ffff88816c0b27b0 by task kworker/u11:1/30582

CPU: 1 UID: 0 PID: 30582 Comm: kworker/u11:1 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(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: hci0 hci_rx_work
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_address_description+0x55/0x1e0
 print_report+0x58/0x70
 kasan_report+0x117/0x150
 l2cap_sock_new_connection_cb+0x208/0x2f0
 l2cap_connect_cfm+0x368/0x1560
 hci_connect_cfm+0x95/0x140
 le_conn_complete_evt+0x1134/0x16b0
 hci_le_conn_complete_evt+0x187/0x470
 hci_event_packet+0x659/0xef0
 hci_rx_work+0x3ee/0x1040
 process_one_work+0x98b/0x1630
 worker_thread+0xb49/0x1140
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 30582:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_noprof+0x3e7/0x7b0
 sk_prot_alloc+0xe7/0x210
 sk_alloc+0x3a/0x390
 bt_sock_alloc+0x3b/0x310
 l2cap_sock_new_connection_cb+0xf1/0x2f0
 l2cap_connect_cfm+0x368/0x1560
 hci_connect_cfm+0x95/0x140
 le_conn_complete_evt+0x1134/0x16b0
 hci_le_conn_complete_evt+0x187/0x470
 hci_event_packet+0x659/0xef0
 hci_rx_work+0x3ee/0x1040
 process_one_work+0x98b/0x1630
 worker_thread+0xb49/0x1140
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30

Freed by task 6628:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x1c5/0x6c0
 __sk_destruct+0x74b/0x9d0
 l2cap_sock_cleanup_listen+0xe0/0x440
 l2cap_sock_release+0x6e/0x270
 __sock_release+0xb9/0x250
 sock_close+0x1c/0x30
 __fput+0x461/0xa70
 task_work_run+0x1d9/0x270
 get_signal+0x11eb/0x1330
 arch_do_signal_or_restart+0xbc/0x840
 exit_to_user_mode_loop+0x8c/0x4d0
 do_syscall_64+0x33e/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88816c0b2000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1968 bytes inside of
 freed 2048-byte region [ffff88816c0b2000, ffff88816c0b2800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16c0b0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x500000000000040(head|node=1|zone=2)
page_type: f5(slab)
raw: 0500000000000040 ffff888100042000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 0500000000000040 ffff888100042000 dead000000000100 dead000000000122
head: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 0500000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 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 3953, tgid 3953 (syz-executor), ts 1610904192585, free_ts 1610855407982
 post_alloc_hook+0x1f9/0x250
 get_page_from_freelist+0x27d6/0x2850
 __alloc_frozen_pages_noprof+0x18d/0x380
 allocate_slab+0x74/0x5e0
 refill_objects+0x33c/0x3d0
 __pcs_replace_empty_main+0x373/0x720
 __kmalloc_node_track_caller_noprof+0x60b/0x7e0
 pskb_expand_head+0x230/0x1390
 netlink_trim+0x1b3/0x2c0
 netlink_broadcast_filtered+0x80/0xea0
 nlmsg_notify+0xf0/0x1a0
 rtnetlink_event+0x224/0x270
 notifier_call_chain+0x1ad/0x3d0
 netif_set_mac_address+0x39f/0x4e0
 do_setlink+0x9bb/0x45a0
 rtnl_newlink+0x15ad/0x1bb0
page last free pid 5665 tgid 5665 stack trace:
 __free_frozen_pages+0x1075/0x11b0
 __slab_free+0x252/0x2a0
 qlist_free_all+0x99/0x100
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 __kmalloc_cache_noprof+0x338/0x690
 nsim_fib_event+0xf36/0xa390
 nsim_fib_event_work+0x26e/0x3e0
 process_one_work+0x98b/0x1630
 worker_thread+0xb8e/0x1140
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30

Memory state around the buggy address:
 ffff88816c0b2680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88816c0b2700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88816c0b2780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff88816c0b2800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88816c0b2880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
