CVE-2026-23461

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user

After commit ab4eedb790ca ("Bluetooth: L2CAP: Fix corrupted list in

hci_chan_del"), l2cap_conn_del() uses conn->lock to protect access to

conn->users. However, l2cap_register_user() and l2cap_unregister_user()

don't use conn->lock, creating a race condition where these functions can

access conn->users and conn->hchan concurrently with l2cap_conn_del().

This can lead to use-after-free and list corruption bugs, as reported

by syzbot.

Fix this by changing l2cap_register_user() and l2cap_unregister_user()

to use conn->lock instead of hci_dev_lock(), ensuring consistent locking

for the l2cap_conn structure.