------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x111/0x130 lib/refcount.c:25, CPU#0: syz.1.205/6402
Modules linked in:
CPU: 0 UID: 0 PID: 6402 Comm: syz.1.205 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:refcount_warn_saturate+0x111/0x130 lib/refcount.c:25
Code: 06 e8 33 91 ec fc 48 8d 3d 3c 19 2f 0c 67 48 0f b9 3a e8 22 91 ec fc 5b 5d c3 cc cc cc cc e8 16 91 ec fc 48 8d 3d 2f 19 2f 0c <67> 48 0f b9 3a e8 05 91 ec fc 5b 5d c3 cc cc cc cc 48 89 df e8 b6
RSP: 0018:ffffc900031dfc90 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888022b7f51c RCX: ffffffff851de1bb
RDX: ffff888032820000 RSI: ffffffff851de26a RDI: ffffffff914cfba0
RBP: 0000000000000002 R08: 0000000000000005 R09: 0000000000000004
R10: 0000000000000002 R11: 0000000000000000 R12: ffff888022b7f51c
R13: ffff8880401ac358 R14: ffffc900031dfd40 R15: ffff888035e9e000
FS:  00007f6652eb86c0(0000) GS:ffff8880d5bde000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9e06f5da08 CR3: 000000003d010000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:289 [inline]
 __refcount_inc include/linux/refcount.h:366 [inline]
 refcount_inc include/linux/refcount.h:383 [inline]
 kref_get include/linux/kref.h:45 [inline]
 config_item_get fs/configfs/item.c:104 [inline]
 config_item_get+0x8c/0xb0 fs/configfs/item.c:101
 configfs_get_config_item fs/configfs/configfs_internal.h:127 [inline]
 get_target fs/configfs/symlink.c:128 [inline]
 configfs_symlink+0x390/0x11f0 fs/configfs/symlink.c:185
 vfs_symlink fs/namei.c:5660 [inline]
 vfs_symlink+0x178/0x4d0 fs/namei.c:5639
 filename_symlinkat+0x2a6/0x560 fs/namei.c:5685
 __do_sys_symlinkat fs/namei.c:5705 [inline]
 __se_sys_symlinkat fs/namei.c:5700 [inline]
 __x64_sys_symlinkat+0x9c/0xe0 fs/namei.c:5700
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6651f9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6652eb8028 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007f6652225fa0 RCX: 00007f6651f9e0d9
RDX: 0000200000000200 RSI: ffffffffffffff9c RDI: 00002000000001c0
RBP: 00007f6652035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6652226038 R14: 00007f6652225fa0 R15: 00007ffd7e1f4b78
 </TASK>
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	e8 33 91 ec fc       	call   0xfcec9138
   5:	48 8d 3d 3c 19 2f 0c 	lea    0xc2f193c(%rip),%rdi        # 0xc2f1948
   c:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  11:	e8 22 91 ec fc       	call   0xfcec9138
  16:	5b                   	pop    %rbx
  17:	5d                   	pop    %rbp
  18:	c3                   	ret
  19:	cc                   	int3
  1a:	cc                   	int3
  1b:	cc                   	int3
  1c:	cc                   	int3
  1d:	e8 16 91 ec fc       	call   0xfcec9138
  22:	48 8d 3d 2f 19 2f 0c 	lea    0xc2f192f(%rip),%rdi        # 0xc2f1958
* 29:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2e:	e8 05 91 ec fc       	call   0xfcec9138
  33:	5b                   	pop    %rbx
  34:	5d                   	pop    %rbp
  35:	c3                   	ret
  36:	cc                   	int3
  37:	cc                   	int3
  38:	cc                   	int3
  39:	cc                   	int3
  3a:	48 89 df             	mov    %rbx,%rdi
  3d:	e8                   	.byte 0xe8
  3e:	b6                   	.byte 0xb6