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BUG: KASAN: use-after-free in rfcomm_dlc_get net/bluetooth/rfcomm/core.c:360 [inline]
BUG: KASAN: use-after-free in rfcomm_dlc_exists+0x16f/0x190 net/bluetooth/rfcomm/core.c:550
Read of size 1 at addr ffff888099922d44 by task syz-executor.4/16865

CPU: 1 PID: 16865 Comm: syz-executor.4 Not tainted 5.6.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:374
 __kasan_report.cold+0x1a/0x32 mm/kasan/report.c:506
 kasan_report+0xe/0x20 mm/kasan/common.c:641
 rfcomm_dlc_get net/bluetooth/rfcomm/core.c:360 [inline]
 rfcomm_dlc_exists+0x16f/0x190 net/bluetooth/rfcomm/core.c:550
 __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:413 [inline]
 rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
 rfcomm_dev_ioctl+0x9ea/0x1d70 net/bluetooth/rfcomm/tty.c:588
 rfcomm_sock_ioctl+0x86/0xb0 net/bluetooth/rfcomm/sock.c:902
 sock_do_ioctl+0xd8/0x2f0 net/socket.c:1053
 sock_ioctl+0x3ed/0x790 net/socket.c:1204
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c849
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f3d411cfc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f3d411d06d4 RCX: 000000000045c849
RDX: 0000000020000100 RSI: 00000000400452c8 RDI: 0000000000000004
RBP: 000000000076bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000316 R14: 00000000004c57dd R15: 000000000076bfac

Allocated by task 32652:
 save_stack+0x1b/0x80 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:515 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:488
 kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 rfcomm_dlc_alloc+0x7a/0x400 net/bluetooth/rfcomm/core.c:305
 rfcomm_sock_alloc.constprop.0+0xad/0x370 net/bluetooth/rfcomm/sock.c:286
 rfcomm_sock_create+0xe0/0x2a0 net/bluetooth/rfcomm/sock.c:329
 bt_sock_create+0x154/0x2a0 net/bluetooth/af_bluetooth.c:130
 __sock_create+0x3cb/0x730 net/socket.c:1433
 sock_create net/socket.c:1484 [inline]
 __sys_socket+0xef/0x200 net/socket.c:1526
 __do_sys_socket net/socket.c:1535 [inline]
 __se_sys_socket net/socket.c:1533 [inline]
 __x64_sys_socket+0x6f/0xb0 net/socket.c:1533
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 16860:
 save_stack+0x1b/0x80 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:476
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 rfcomm_dlc_put include/net/bluetooth/rfcomm.h:258 [inline]
 __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:417 [inline]
 rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
 rfcomm_dev_ioctl+0x1a8c/0x1d70 net/bluetooth/rfcomm/tty.c:588
 rfcomm_sock_ioctl+0x86/0xb0 net/bluetooth/rfcomm/sock.c:902
 sock_do_ioctl+0xd8/0x2f0 net/socket.c:1053
 sock_ioctl+0x3ed/0x790 net/socket.c:1204
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888099922c00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 324 bytes inside of
 512-byte region [ffff888099922c00, ffff888099922e00)
The buggy address belongs to the page:
page:ffffea0002664880 refcount:1 mapcount:0 mapping:ffff8880aa000a80 index:0xffff888099922800
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea000219c248 ffffea00028b5f08 ffff8880aa000a80
raw: ffff888099922800 ffff888099922000 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888099922c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888099922c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888099922d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888099922d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888099922e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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