------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 2 PID: 8431 at lib/refcount.c:25 refcount_warn_saturate+0x1ca/0x210 lib/refcount.c:25
Modules linked in:
CPU: 2 PID: 8431 Comm: syz-executor.2 Not tainted 6.9.0-rc4-syzkaller-00164-gdbe0a7be2838 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:refcount_warn_saturate+0x1ca/0x210 lib/refcount.c:25
Code: ff 89 de e8 d8 28 0e fd 84 db 0f 85 e6 fe ff ff e8 4b 2e 0e fd c6 05 2a 45 09 0b 01 90 48 c7 c7 40 f4 6e 8b e8 c7 9c d0 fc 90 <0f> 0b 90 90 e9 c3 fe ff ff e8 28 2e 0e fd c6 05 05 45 09 0b 01 90
RSP: 0018:ffffc9000359f898 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc90008862000
RDX: 0000000000040000 RSI: ffffffff81503286 RDI: 0000000000000001
RBP: ffff88802e8a1d8c R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000002 R12: ffff88802e8a1d8c
R13: dffffc0000000000 R14: 1ffff920006b3f17 R15: 0000000000000000
FS:  00007f3a441866c0(0000) GS:ffff88806b400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555581ef1978 CR3: 0000000024f10000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:190 [inline]
 __refcount_inc include/linux/refcount.h:241 [inline]
 refcount_inc include/linux/refcount.h:258 [inline]
 p9_fid_get include/net/9p/client.h:262 [inline]
 v9fs_fid_find+0x2e2/0x330 fs/9p/fid.c:129
 v9fs_fid_lookup_with_uid fs/9p/fid.c:181 [inline]
 v9fs_fid_lookup+0xd8/0xf20 fs/9p/fid.c:314
 v9fs_fid_clone fs/9p/fid.h:29 [inline]
 v9fs_file_open+0x5f0/0xba0 fs/9p/vfs_file.c:56
 do_dentry_open+0x8da/0x18c0 fs/open.c:955
 do_open fs/namei.c:3642 [inline]
 path_openat+0x1dfb/0x2990 fs/namei.c:3799
 do_filp_open+0x1dc/0x430 fs/namei.c:3826
 do_sys_openat2+0x17a/0x1e0 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_creat fs/open.c:1497 [inline]
 __se_sys_creat fs/open.c:1491 [inline]
 __x64_sys_creat+0xcd/0x120 fs/open.c:1491
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3a4347dea9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3a441860c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007f3a435abf80 RCX: 00007f3a4347dea9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200000c0
RBP: 00007f3a434ca4a4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f3a435abf80 R15: 00007fffa780ab68
 </TASK>