[moderation] [media?] WARNING: refcount bug in dvb_device_open (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e53642b87a4f Merge tag 'v6.18-rc3-smb-server-fixes' of git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12e3be7c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=19d831c6d0386a9c
dashboard link: https://syzkaller.appspot.com/bug?extid=969c44d6fcfad176dd11
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-...@vger.kernel.org linux...@vger.kernel.org mch...@kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e37bab63d8c6/disk-e53642b8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/97e1bf59f467/vmlinux-e53642b8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ead1577e60ab/bzImage-e53642b8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+969c44...@syzkaller.appspotmail.com

------------[ cut here ]------------
refcount_t: saturated; leaking memory.
WARNING: CPU: 0 PID: 16030 at lib/refcount.c:22 refcount_warn_saturate+0xd4/0x210 lib/refcount.c:22
Modules linked in:
CPU: 0 UID: 0 PID: 16030 Comm: syz.3.2381 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:refcount_warn_saturate+0xd4/0x210 lib/refcount.c:22
Code: e9 c8 0b 31 ff 89 de e8 ea 95 1a fd 84 db 75 dc e8 01 9b 1a fd c6 05 07 e9 c8 0b 01 90 48 c7 c7 80 c0 ef 8b e8 6d 1c d9 fc 90 <0f> 0b 90 90 eb bc e8 e1 9a 1a fd 0f b6 1d e8 e8 c8 0b 31 ff 89 de
RSP: 0018:ffffc90004c57908 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000ce0d000
RDX: 0000000000080000 RSI: ffffffff817aee65 RDI: 0000000000000001
RBP: ffff88802a112e10 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 00000000000184f0 R12: ffff88801ba94e00
R13: ffff888030fd0d80 R14: ffff88802a4248a8 R15: ffff88802a112e10
FS: 00007f8f948b36c0(0000) GS:ffff888124a10000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555b86b91950 CR3: 0000000049168000 CR4: 00000000003526f0
Call Trace:
<TASK>
__refcount_add include/linux/refcount.h:291 [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]
dvb_device_get drivers/media/dvb-core/dvbdev.c:624 [inline]
dvb_device_open+0x2ed/0x3b0 drivers/media/dvb-core/dvbdev.c:106
chrdev_open+0x234/0x6a0 fs/char_dev.c:414
do_dentry_open+0x982/0x1530 fs/open.c:965
vfs_open+0x82/0x3f0 fs/open.c:1097
do_open fs/namei.c:3975 [inline]
path_openat+0x1de4/0x2cb0 fs/namei.c:4134
do_filp_open+0x20b/0x470 fs/namei.c:4161
do_sys_openat2+0x11b/0x1d0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x174/0x210 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8f9398efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8f948b3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f8f93be5fa0 RCX: 00007f8f9398efc9
RDX: 0000000000000001 RSI: 0000200000000080 RDI: ffffffffffffff9c
RBP: 00007f8f93a11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8f93be6038 R14: 00007f8f93be5fa0 R15: 00007ffc713e2848
</TASK>


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