------------[ 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#3: syz.3.850/9235
Modules linked in:
CPU: 3 UID: 0 PID: 9235 Comm: syz.3.850 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: cc e8 43 e6 ed fc 48 8d 3d dc 0f 12 0c 67 48 0f b9 3a e8 32 e6 ed fc 5b 5d e9 0b 8b a0 06 e8 26 e6 ed fc 48 8d 3d cf 0f 12 0c <67> 48 0f b9 3a e8 15 e6 ed fc 5b 5d c3 cc cc cc cc 48 89 df e8 c6
RSP: 0018:ffffc90003b57c78 EFLAGS: 00010287
RAX: 0000000000000f82 RBX: ffff88802860d31c RCX: ffffc9000cc04000
RDX: 0000000000080000 RSI: ffffffff851bc7da RDI: ffffffff912dd7b0
RBP: 0000000000000002 R08: 0000000000000005 R09: 0000000000000004
R10: 0000000000000002 R11: 0000000000000000 R12: ffff88802860d31c
R13: ffff88801327c358 R14: ffffc90003b57d28 R15: ffff88806d173000
FS:  0000000000000000(0000) GS:ffff888096edf000(0063) knlGS:00000000f5476b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000051120000 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]
 __ia32_sys_symlinkat+0x9b/0xe0 fs/namei.c:5700
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307
 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7fb3fec
Code: Unable to access opcode bytes at 0xf7fb3fc2.
RSP: 002b:00000000f547650c EFLAGS: 00000292 ORIG_RAX: 0000000000000130
RAX: ffffffffffffffda RBX: 00000000800001c0 RCX: 00000000ffffff9c
RDX: 0000000080000200 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess):
   0:	cc                   	int3
   1:	e8 43 e6 ed fc       	call   0xfcede649
   6:	48 8d 3d dc 0f 12 0c 	lea    0xc120fdc(%rip),%rdi        # 0xc120fe9
   d:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  12:	e8 32 e6 ed fc       	call   0xfcede649
  17:	5b                   	pop    %rbx
  18:	5d                   	pop    %rbp
  19:	e9 0b 8b a0 06       	jmp    0x6a08b29
  1e:	e8 26 e6 ed fc       	call   0xfcede649
  23:	48 8d 3d cf 0f 12 0c 	lea    0xc120fcf(%rip),%rdi        # 0xc120ff9
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e8 15 e6 ed fc       	call   0xfcede649
  34:	5b                   	pop    %rbx
  35:	5d                   	pop    %rbp
  36:	c3                   	ret
  37:	cc                   	int3
  38:	cc                   	int3
  39:	cc                   	int3
  3a:	cc                   	int3
  3b:	48 89 df             	mov    %rbx,%rdi
  3e:	e8                   	.byte 0xe8
  3f:	c6                   	.byte 0xc6