------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 15105 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Modules linked in:
CPU: 1 PID: 15105 Comm: syz-executor.2 Not tainted 5.16.0-rc3-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Code: 09 31 ff 89 de e8 57 e7 9c fd 84 db 0f 85 36 ff ff ff e8 6a e3 9c fd 48 c7 c7 60 d4 04 8a c6 05 9a ef a1 09 01 e8 31 c9 25 05 <0f> 0b e9 17 ff ff ff e8 4b e3 9c fd 0f b6 1d 7f ef a1 09 31 ff 89
RSP: 0018:ffffc90024877b80 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff815f0d88 RDI: fffff5200490ef62
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff815eab2e R11: 0000000000000000 R12: ffff88807647a780
R13: ffff88807647a78c R14: 1ffff9200490ef75 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88802cb00000(0063) knlGS:00000000f44e1b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000ffa64ec4 CR3: 0000000049297000 CR4: 0000000000152ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:199 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 v9fs_fid_find+0x471/0x4e0 fs/9p/fid.c:111
 v9fs_fid_lookup_with_uid+0xa2/0xae0 fs/9p/fid.c:160
 v9fs_vfs_getattr_dotl+0xd3/0x2c0 fs/9p/vfs_inode_dotl.c:479
 vfs_getattr_nosec+0x2b4/0x370 fs/stat.c:123
 vfs_getattr fs/stat.c:160 [inline]
 vfs_statx+0x18d/0x390 fs/stat.c:225
 vfs_fstatat fs/stat.c:243 [inline]
 vfs_stat include/linux/fs.h:3353 [inline]
 __do_compat_sys_newstat+0x91/0x110 fs/stat.c:682
 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
 __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf6ee7549
Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f44e15fc EFLAGS: 00000296 ORIG_RAX: 000000000000006a
RAX: ffffffffffffffda RBX: 0000000020000f00 RCX: 0000000020000f40
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess):
   0:	03 74 c0 01          	add    0x1(%rax,%rax,8),%esi
   4:	10 05 03 74 b8 01    	adc    %al,0x1b87403(%rip)        # 0x1b8740d
   a:	10 06                	adc    %al,(%rsi)
   c:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
  10:	10 07                	adc    %al,(%rdi)
  12:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
  16:	10 08                	adc    %cl,(%rax)
  18:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1c:	00 00                	add    %al,(%rax)
  1e:	00 00                	add    %al,(%rax)
  20:	00 51 52             	add    %dl,0x52(%rcx)
  23:	55                   	push   %rbp
  24:	89 e5                	mov    %esp,%ebp
  26:	0f 34                	sysenter
  28:	cd 80                	int    $0x80
* 2a:	5d                   	pop    %rbp <-- trapping instruction
  2b:	5a                   	pop    %rdx
  2c:	59                   	pop    %rcx
  2d:	c3                   	retq
  2e:	90                   	nop
  2f:	90                   	nop
  30:	90                   	nop
  31:	90                   	nop
  32:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  39:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi