In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: ISO: fix use-after-free of listener socket in iso_conn_ready
iso_conn_ready() looks up the BIS listener socket with iso_get_sock(),
which takes a reference, and then, without re-checking its state,
creates a child socket from it:
<pre>
parent = iso_get_sock(hdev, ...);
if (!parent)
return;
lock_sock(parent);
sk = iso_sock_alloc(sock_net(parent), NULL, BTPROTO_ISO, ...);
...
iso_chan_add(conn, sk, parent);
...
release_sock(parent);
sock_put(parent);
</pre>
If the listener socket is closed concurrently, between iso_get_sock()
and lock_sock(), the reference taken by iso_get_sock() may be the last
one: the close path drops the link-list reference, and once
iso_conn_ready() drops its own reference at the end of the function the
socket is freed. The child socket, however, is already linked to the
freed parent, and a later disconnect of the child runs iso_chan_del()
-> bt_accept_unlink(), which dereferences the dangling parent pointer
into the freed accept queue (a use-after-free). The same dangling
pointer is also dereferenced through parent->***() in
iso_chan_del().
Fix it the same way the connected (non-BIS) path was fixed in commit
0d255e63fcf3 ("Bluetooth: ISO: hold sk properly in iso_conn_ready"):
after taking the socket lock, re-check that the parent is still a
listening, alive socket, and bail out otherwise.
CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 8.8
AV:A - The UAF is in Bluetooth ISO iso_conn_ready() parent-lookup for incoming CIS/BIS/PA; that path runs from HCI connect_cfm events (hci_le_cis_req_evt, BIG/PA sync) driven by LE isochronous traffic from peers in radio range, which is an adjacent attack surface.
AC:L - This is a use-after-free race between iso_get_sock() and listener close (iso_sock_release/iso_sock_kill) before lock_sock(); an attacker who opens/closes an ISO listen socket while concurrent HCI CIS/BIS/PA completion runs controls both sides and can trigger it without uncontrollable conditions.
PR:N - iso_sock_create has no capability check, and the vulnerable path is reached from unauthenticated HCI CIS/BIG/PA events processed for any Bluetooth-enabled device in range; listener close can occur from automatic LE Audio/bluetoothd teardown without privileged local credentials.
UI:N - No victim action is required: iso_connect_ind returns HCI_LM_ACCEPT so incoming CIS/BIS/PA sync is auto-accepted when an ISO listener exists, and OS LE Audio stacks keep such listeners during normal broadcast/unicast operation.
S:U - The UAF corrupts kernel socket/accept-queue memory and can enable privilege escalation within the host kernel; it does not cross a VM, container, or IOMMU security boundary, so scope remains unchanged.
C:H - Use-after-free of the listener struct sock (and later bt_accept_unlink of the dangling parent) lets an attacker reuse the freed sock/accept-queue object, enabling arbitrary kernel memory disclosure via heap grooming per UAF guidance.
I:H - The child is linked to the freed parent via iso_chan_add/bt_accept_enqueue; later iso_chan_del -> bt_accept_unlink writes the freed parent's accept queue (list_del, sk_acceptq_removed), a kernel heap write primitive usable for control-flow hijack.
A:H - Dereferencing the freed listener in iso_chan_del/bt_accept_unlink (accept_q_lock, list, parent->sk_data_ready) causes kernel oops/panic; UAFs in this ISO path are a high availability impact even before full exploitation.
| Attack Vector |
Adjacent Network |
Scope |
Unchanged |
| Attack Complexity |
Low |
Confidentiality Impact |
High |
| Privileges Required |
None |
Integrity Impact |
High |
| User Interaction |
None |
Availability Impact |
High |
AV:A - The UAF is in Bluetooth ISO iso_conn_ready() parent-lookup for incoming CIS/BIS/PA; that path runs from HCI connect_cfm events (hci_le_cis_req_evt, BIG/PA sync) driven by LE isochronous traffic from peers in radio range, which is an adjacent attack surface.
AC:L - This is a use-after-free race between iso_get_sock() and listener close (iso_sock_release/iso_sock_kill) before lock_sock(); an attacker who opens/closes an ISO listen socket while concurrent HCI CIS/BIS/PA completion runs controls both sides and can trigger it without uncontrollable conditions.
PR:N - iso_sock_create has no capability check, and the vulnerable path is reached from unauthenticated HCI CIS/BIG/PA events processed for any Bluetooth-enabled device in range; listener close can occur from automatic LE Audio/bluetoothd teardown without privileged local credentials.
UI:N - No victim action is required: iso_connect_ind returns HCI_LM_ACCEPT so incoming CIS/BIS/PA sync is auto-accepted when an ISO listener exists, and OS LE Audio stacks keep such listeners during normal broadcast/unicast operation.
S:U - The UAF corrupts kernel socket/accept-queue memory and can enable privilege escalation within the host kernel; it does not cross a VM, container, or IOMMU security boundary, so scope remains unchanged.
C:H - Use-after-free of the listener struct sock (and later bt_accept_unlink of the dangling parent) lets an attacker reuse the freed sock/accept-queue object, enabling arbitrary kernel memory disclosure via heap grooming per UAF guidance.
I:H - The child is linked to the freed parent via iso_chan_add/bt_accept_enqueue; later iso_chan_del -> bt_accept_unlink writes the freed parent's accept queue (list_del, sk_acceptq_removed), a kernel heap write primitive usable for control-flow hijack.
A:H - Dereferencing the freed listener in iso_chan_del/bt_accept_unlink (accept_q_lock, list, parent->sk_data_ready) causes kernel oops/panic; UAFs in this ISO path are a high availability impact even before full exploitation.
CVSS 3.1