audit: type=1326 audit(1619609853.411:82): auid=4294967295 uid=0 gid=0 ses=4294967295 pid=18065 comm="syz-executor.5" exe="/root/syz-executor.5" sig=9 arch=c000003e syscall=231 compat=0 ip=0x4665f9 code=0x0
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x2c57/0x3f20 kernel/locking/lockdep.c:3369
Read of size 8 at addr ffff8880938011a0 by task kworker/1:3/7724

CPU: 1 PID: 7724 Comm: kworker/1:3 Not tainted 4.14.232-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
 __lock_acquire+0x2c57/0x3f20 kernel/locking/lockdep.c:3369
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:176
 spin_lock_bh include/linux/spinlock.h:322 [inline]
 lock_sock_nested+0x39/0x100 net/core/sock.c:2788
 l2cap_sock_teardown_cb+0x93/0x650 net/bluetooth/l2cap_sock.c:1341
 l2cap_chan_del+0xaf/0x950 net/bluetooth/l2cap_core.c:599
 l2cap_chan_close+0x103/0x870 net/bluetooth/l2cap_core.c:757
 l2cap_chan_timeout+0x143/0x2a0 net/bluetooth/l2cap_core.c:430
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 17810:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 __do_kmalloc_node mm/slab.c:3682 [inline]
 __kmalloc_node_track_caller+0x4c/0x70 mm/slab.c:3696
 __kmalloc_reserve net/core/skbuff.c:137 [inline]
 __alloc_skb+0x96/0x510 net/core/skbuff.c:205
 alloc_skb include/linux/skbuff.h:980 [inline]
 alloc_skb_with_frags+0x85/0x500 net/core/skbuff.c:5255
 sock_alloc_send_pskb+0x577/0x6d0 net/core/sock.c:2083
 mld_newpack+0x1cb/0x720 net/ipv6/mcast.c:1585
 add_grhead+0x265/0x330 net/ipv6/mcast.c:1691
 add_grec+0xc40/0xed0 net/ipv6/mcast.c:1822
 mld_send_cr net/ipv6/mcast.c:1948 [inline]
 mld_ifc_timer_expire+0x508/0xcd0 net/ipv6/mcast.c:2455
 call_timer_fn+0x14a/0x650 kernel/time/timer.c:1280
 expire_timers+0x232/0x4d0 kernel/time/timer.c:1319
 __run_timers kernel/time/timer.c:1637 [inline]
 run_timer_softirq+0x1d5/0x5a0 kernel/time/timer.c:1650
 __do_softirq+0x24d/0x9ff kernel/softirq.c:288

Freed by task 17810:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 skb_free_head net/core/skbuff.c:563 [inline]
 skb_release_data+0x5f6/0x820 net/core/skbuff.c:583
 skb_release_all net/core/skbuff.c:640 [inline]
 __kfree_skb net/core/skbuff.c:654 [inline]
 kfree_skb+0xe7/0x390 net/core/skbuff.c:672
 ip6gre_tunnel_xmit+0x5f7/0xe50 net/ipv6/ip6_gre.c:716
 __netdev_start_xmit include/linux/netdevice.h:4051 [inline]
 netdev_start_xmit include/linux/netdevice.h:4060 [inline]
 xmit_one net/core/dev.c:3005 [inline]
 dev_hard_start_xmit+0x188/0x890 net/core/dev.c:3021
 sch_direct_xmit+0x251/0x500 net/sched/sch_generic.c:186
 __dev_xmit_skb net/core/dev.c:3214 [inline]
 __dev_queue_xmit+0x1ab0/0x2480 net/core/dev.c:3489
 neigh_hh_output include/net/neighbour.h:490 [inline]
 neigh_output include/net/neighbour.h:498 [inline]
 ip6_finish_output2+0xc6a/0x1f10 net/ipv6/ip6_output.c:120
 ip6_finish_output+0x5c6/0xd50 net/ipv6/ip6_output.c:192
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip6_output+0x1c5/0x660 net/ipv6/ip6_output.c:209
 dst_output include/net/dst.h:470 [inline]
 NF_HOOK include/linux/netfilter.h:250 [inline]
 mld_sendpack+0x5fe/0xea0 net/ipv6/mcast.c:1660
 mld_send_cr net/ipv6/mcast.c:1956 [inline]
 mld_ifc_timer_expire+0x57c/0xcd0 net/ipv6/mcast.c:2455
 call_timer_fn+0x14a/0x650 kernel/time/timer.c:1280
 expire_timers+0x232/0x4d0 kernel/time/timer.c:1319
 __run_timers kernel/time/timer.c:1637 [inline]
 run_timer_softirq+0x1d5/0x5a0 kernel/time/timer.c:1650
 __do_softirq+0x24d/0x9ff kernel/softirq.c:288

The buggy address belongs to the object at ffff888093801100
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 160 bytes inside of
 2048-byte region [ffff888093801100, ffff888093801900)
The buggy address belongs to the page:
page:ffffea00024e0000 count:1 mapcount:0 mapping:ffff888093800000 index:0x0 compound_mapcount: 0
flags: 0xfff00000008100(slab|head)
raw: 00fff00000008100 ffff888093800000 0000000000000000 0000000100000003
raw: ffffea00019591a0 ffffea00024d4620 ffff88813fe80c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888093801080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888093801100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888093801180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff888093801200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888093801280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================