[syzbot] [input?] INFO: trying to register non-static key in roccat_open

[syzbot] [input?] INFO: trying to register non-static key in roccat_open

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    bc35965f6940 Merge tag 'mm-hotfixes-stable-2026-09-03-17-4..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1066ab49580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b454dc6b1b7acd30
dashboard link: https://syzkaller.appspot.com/bug?extid=9f7405999979761b6cfc
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8cbf7acceedb/disk-bc35965f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/203c0c282c1c/vmlinux-bc35965f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/de1170205619/bzImage-bc35965f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9f7405999979761b6cfc@syzkaller.appspotmail.com

INFO: trying to register non-static key.
The code is fine but needs lockdep annotation, or maybe
you didn't initialize this object before use?
turning off the locking correctness validator.
CPU: 1 UID: 0 PID: 7946 Comm: syz.4.562 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 assign_lock_key+0x133/0x150 kernel/locking/lockdep.c:1000
 register_lock_class+0xcc/0x2e0 kernel/locking/lockdep.c:1315
 __lock_acquire+0xaf/0x2e40 kernel/locking/lockdep.c:5128
 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
 __mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
 mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
 roccat_open+0xf6/0x5d0 drivers/hid/hid-roccat.c:178
 chrdev_open+0x4dc/0x600 fs/char_dev.c:411
 do_dentry_open+0x849/0x1420 fs/open.c:996
 vfs_open+0x3b/0x350 fs/open.c:1101
 do_open fs/namei.c:4837 [inline]
 path_openat+0x1448/0x1d60 fs/namei.c:5000
 do_file_open+0x23e/0x4a0 fs/namei.c:5029
 do_sys_openat2+0x115/0x200 fs/open.c:1417
 do_sys_open fs/open.c:1423 [inline]
 __do_sys_openat fs/open.c:1439 [inline]
 __se_sys_openat fs/open.c:1434 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1434
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fde12ede159
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:00007fde11136028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fde13165fa0 RCX: 00007fde12ede159
RDX: 0000000000000002 RSI: 0000200000000100 RDI: ffffffffffffff9c
RBP: 00007fde12f75024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fde13166038 R14: 00007fde13165fa0 R15: 00007ffe150b2898
 </TASK>


---
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[PATCH] HID: roccat: fully initialize device before publishing to devices[]

[Ivy Lopez]

roccat_connect() published the new device into the global devices[]
array, then released devices_lock, before initializing readers_lock,
cbuf_lock, the wait queue, the readers list, or setting hid/exist/
cbuf_end/report_size on the device.

Since devices[] is checked (under devices_lock) by roccat_open() to
decide whether a device is available to open, a concurrent open()
racing against roccat_connect() could look up the device, then lock
readers_lock before mutex_init() has run on it, or read device->hid
while it is still NULL from kzalloc, once devices_lock is released
but before the remaining fields are set.

Move all initialization of the device's own private state ahead of
the point where it is inserted into devices[], so the object is fully
constructed before it becomes visible to any other reader.

Reported-by: syzbot+9f7405999979761b6cfc@syzkaller.appspotmail.com
Signed-off-by: Ivy Lopez <skunkolee@gmail.com>
---
 drivers/hid/hid-roccat.c | 29 ++++++++++++-----------------
 1 file changed, 12 insertions(+), 17 deletions(-)

diff --git a/drivers/hid/hid-roccat.c b/drivers/hid/hid-roccat.c
index d6fff53d4ee7..53358297e96c 100644
--- a/drivers/hid/hid-roccat.c
+++ b/drivers/hid/hid-roccat.c
@@ -307,26 +307,32 @@ int roccat_connect(const struct class *klass, struct hid_device *hid, int report
 	if (!device)
 		return -ENOMEM;
 
-	mutex_lock(&devices_lock);
+	init_waitqueue_head(&device->wait);
+	INIT_LIST_HEAD(&device->readers);
+	mutex_init(&device->readers_lock);
+	mutex_init(&device->cbuf_lock);
+	device->hid = hid;
+	device->exist = 1;
+	device->cbuf_end = 0;
+	device->report_size = report_size;
 
+	mutex_lock(&devices_lock);
 	for (minor = 0; minor < ROCCAT_MAX_DEVICES; ++minor) {
 		if (devices[minor])
 			continue;
 		break;
 	}
-
-	if (minor < ROCCAT_MAX_DEVICES) {
-		devices[minor] = device;
-	} else {
+	if (minor >= ROCCAT_MAX_DEVICES) {
 		mutex_unlock(&devices_lock);
 		kfree(device);
 		return -EINVAL;
 	}
+	device->minor = minor;
+	devices[minor] = device;
 
 	device->dev = device_create(klass, &hid->dev,
 			MKDEV(roccat_major, minor), NULL,
 			"%s%s%d", "roccat", hid->driver->name, minor);
-
 	if (IS_ERR(device->dev)) {
 		devices[minor] = NULL;
 		mutex_unlock(&devices_lock);
@@ -334,19 +340,8 @@ int roccat_connect(const struct class *klass, struct hid_device *hid, int report
 		kfree(device);
 		return temp;
 	}
-
 	mutex_unlock(&devices_lock);
 
-	init_waitqueue_head(&device->wait);
-	INIT_LIST_HEAD(&device->readers);
-	mutex_init(&device->readers_lock);
-	mutex_init(&device->cbuf_lock);
-	device->minor = minor;
-	device->hid = hid;
-	device->exist = 1;
-	device->cbuf_end = 0;
-	device->report_size = report_size;
-
 	return minor;
 }
 EXPORT_SYMBOL_GPL(roccat_connect);
-- 
2.55.0