Re: [syzbot] [bluetooth?] BUG: corrupted list in _hci_cmd_sync_cancel_entry

[Hillf Danton <hdanton@sina.com>]

> Date: Wed, 25 Jun 2025 10:14:27 -0700
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    7595b66ae9de Merge tag 'selinux-pr-20250624' of git://git...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10ed4f0c580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=641bc01f4fbdccd4
> dashboard link: https://syzkaller.appspot.com/bug?extid=01fdb2cc3f0b4ddcfcf1
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14bc9b70580000

#syz test

--- x/net/bluetooth/hci_sync.c
+++ y/net/bluetooth/hci_sync.c
@@ -862,14 +862,17 @@ bool hci_cmd_sync_dequeue_once(struct hc
 			       void *data, hci_cmd_sync_work_destroy_t destroy)
 {
 	struct hci_cmd_sync_work_entry *entry;
+	bool ret = false;
 
-	entry = hci_cmd_sync_lookup_entry(hdev, func, data, destroy);
-	if (!entry)
-		return false;
+	mutex_lock(&hdev->cmd_sync_work_lock);
+	entry = _hci_cmd_sync_lookup_entry(hdev, func, data, destroy);
+	if (entry) {
+		_hci_cmd_sync_cancel_entry(hdev, entry, -ECANCELED);
+		ret = true;
+	}
+	mutex_unlock(&hdev->cmd_sync_work_lock);
 
-	hci_cmd_sync_cancel_entry(hdev, entry);
-
-	return true;
+	return ret;
 }
 EXPORT_SYMBOL(hci_cmd_sync_dequeue_once);
 
--