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BUG: KASAN: use-after-free in constant_test_bit arch/x86/include/asm/bitops.h:328 [inline]
BUG: KASAN: use-after-free in sock_flag include/net/sock.h:810 [inline]
BUG: KASAN: use-after-free in l2cap_sock_kill net/bluetooth/l2cap_sock.c:1047 [inline]
BUG: KASAN: use-after-free in l2cap_sock_close_cb+0xa7/0xb0 net/bluetooth/l2cap_sock.c:1312
Read of size 8 at addr ffff888053956660 by task kworker/0:2/2738

CPU: 0 PID: 2738 Comm: kworker/0:2 Not tainted 4.14.198-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+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
 constant_test_bit arch/x86/include/asm/bitops.h:328 [inline]
 sock_flag include/net/sock.h:810 [inline]
 l2cap_sock_kill net/bluetooth/l2cap_sock.c:1047 [inline]
 l2cap_sock_close_cb+0xa7/0xb0 net/bluetooth/l2cap_sock.c:1312
 l2cap_chan_timeout+0x182/0x1e0 net/bluetooth/l2cap_core.c:431
 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 10160:
 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 mm/slab.c:3720 [inline]
 __kmalloc+0x15a/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 sk_prot_alloc+0x1ba/0x290 net/core/sock.c:1467
 sk_alloc+0x36/0xcd0 net/core/sock.c:1521
 l2cap_sock_alloc.constprop.0+0x31/0x210 net/bluetooth/l2cap_sock.c:1591
 l2cap_sock_create+0xdd/0x170 net/bluetooth/l2cap_sock.c:1637
 bt_sock_create+0x13b/0x280 net/bluetooth/af_bluetooth.c:130
 __sock_create+0x303/0x620 net/socket.c:1275
 rfcomm_l2sock_create net/bluetooth/rfcomm/core.c:203 [inline]
 rfcomm_session_create net/bluetooth/rfcomm/core.c:738 [inline]
 __rfcomm_dlc_open net/bluetooth/rfcomm/core.c:388 [inline]
 rfcomm_dlc_open+0x6ec/0xc00 net/bluetooth/rfcomm/core.c:431
 rfcomm_sock_connect+0x2c6/0x3c0 net/bluetooth/rfcomm/sock.c:415
 SYSC_connect net/socket.c:1655 [inline]
 SyS_connect+0x1f4/0x240 net/socket.c:1636
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 3542:
 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
 sk_prot_free net/core/sock.c:1504 [inline]
 __sk_destruct+0x577/0x6e0 net/core/sock.c:1582
 sk_destruct net/core/sock.c:1597 [inline]
 __sk_free+0xd9/0x2d0 net/core/sock.c:1605
 sk_free+0x2b/0x40 net/core/sock.c:1616
 sock_put include/net/sock.h:1662 [inline]
 l2cap_sock_kill.part.0+0x5b/0x70 net/bluetooth/l2cap_sock.c:1056
 l2cap_sock_kill net/bluetooth/l2cap_sock.c:1207 [inline]
 l2cap_sock_release+0x146/0x180 net/bluetooth/l2cap_sock.c:1205
 __sock_release net/socket.c:602 [inline]
 sock_release+0x87/0x1e0 net/socket.c:623
 rfcomm_session_del+0x14f/0x1e0 net/bluetooth/rfcomm/core.c:684
 rfcomm_session_close net/bluetooth/rfcomm/core.c:723 [inline]
 rfcomm_process_rx net/bluetooth/rfcomm/core.c:1916 [inline]
 rfcomm_process_sessions net/bluetooth/rfcomm/core.c:2000 [inline]
 rfcomm_run+0x1127/0x3ca0 net/bluetooth/rfcomm/core.c:2087
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff888053956600
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 96 bytes inside of
 2048-byte region [ffff888053956600, ffff888053956e00)
The buggy address belongs to the page:
page:ffffea00014e5580 count:1 mapcount:0 mapping:ffff888053956600 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff888053956600 0000000000000000 0000000100000003
raw: ffffea00029e2220 ffffea0002371320 ffff88812fe50c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888053956500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888053956580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888053956600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff888053956680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888053956700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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