In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: access chan->conn safely in get/setsockopt
Since commit b66774b48dd9 ("Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref")
l2cap_chan::conn has held reference and remains non-NULL also after the
corresponding hci_conn is deleted. In this state accessing various
fields eg. hci_conn::hdev is invalid, which leads to KASAN crash in
l2cap_sock_setsockopt() access of conn->hcon->hdev. Check l2cap_chan::conn.hcon corresponds to an alive hci_conn before
trying to use it in l2cap_sock.c.
Hold l2cap_chan_lock() in
getsockopt/setsockopt to ensure it stays alive, and to avoid data races
in l2cap_chan fields.
Attack Parameters
Attack Vector
Local
Requires local access
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v3.1