In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_conn: Lock parent access during enhanced SCO setup
Bluetooth: hci_conn: Lock parent access during enhanced SCO setup
hci_enhanced_setup_sync() runs on the request workqueue without the
hci_dev_lock held by its caller when setup was queued. Its CVSD
capability check and find_next_esco_param() dereference conn->parent
while the receive workqueue can unlink and release that parent.
The following interleaving can cause a use-after-free:
hci_enhanced_setup_sync() hci_disconn_complete_evt()
load conn->parent
hci_dev_lock()
hci_conn_del(ACL parent)
unlink SCO child
drop link's parent reference
clear child->parent
release ACL parent
bt_link_release()
kfree(parent)
hci_dev_unlock()
read parent->features[0][3]
The reference held for the queued SCO child does not keep its ACL parent
alive after unlinking. Commit 42de40abe25d ("Bluetooth: hci_conn: fix the
SCO setup context lifetime") protects the child stored in the queued
context, but leaves these parent accesses unprotected.
With a 40 ms diagnostic delay after loading conn->parent, an instrumented
kernel based on fd179f8a05be, which already contains 42de40abe25d,
BUG: KASAN: slab-use-after-free in hci_enhanced_setup_sync+0xda5/0xdf0
Read of size 1 at addr ffff888102204047 by task kworker/u17:0/93
Call Trace:
hci_enhanced_setup_sync+0xda5/0xdf0
hci_cmd_sync_work+0x13c/0x290
process_one_work+0x6b4/0x10e0
Allocated by task 92:
__hci_conn_add+0x304/0x1df0
hci_connect_acl+0x349/0x3e0
hci_connect_sco+0x3b/0x9a0
sco_sock_connect+0x475/0xca0
Freed by task 94:
kfree+0x121/0x3c0
bt_link_release+0x79/0xa0
device_release+0xc8/0x240
kobject_put+0x14d/0x280
hci_conn_del+0x524/0xe30
hci_disconn_complete_evt+0x403/0x8c0
hci_event_packet+0x71b/0xb20
hci_rx_work+0x293/0x730
The accessed address is 71 bytes into the freed ACL parent, at its
features[0][3] byte; the queued SCO child is a different object. The
diagnostic preserves the loaded parent across the delay, matching the
unmodified compiled capability check, and does not change the parent
references or teardown path.
Hold hci_dev_lock() across the codec switch, including every call to
find_next_esco_param(), and release it on all selection errors. Keep
configure_datapath_sync() outside the critical section because it waits
for HCI events. Preserve parameter selection and existing return values.
Bluetooth: hci_conn: Lock parent access during enhanced SCO setup
Bluetooth: hci_conn: Lock parent access during enhanced SCO setup
hci_enhanced_setup_sync() runs on the request workqueue without the
hci_dev_lock held by its caller when setup was queued. Its CVSD
capability check and find_next_esco_param() dereference conn->parent
while the receive workqueue can unlink and release that parent.
The following interleaving can cause a use-after-free:
hci_enhanced_setup_sync() hci_disconn_complete_evt()
load conn->parent
hci_dev_lock()
hci_conn_del(ACL parent)
unlink SCO child
drop link's parent reference
clear child->parent
release ACL parent
bt_link_release()
kfree(parent)
hci_dev_unlock()
read parent->features[0][3]
The reference held for the queued SCO child does not keep its ACL parent
alive after unlinking. Commit 42de40abe25d ("Bluetooth: hci_conn: fix the
SCO setup context lifetime") protects the child stored in the queued
context, but leaves these parent accesses unprotected.
With a 40 ms diagnostic delay after loading conn->parent, an instrumented
kernel based on fd179f8a05be, which already contains 42de40abe25d,
BUG: KASAN: slab-use-after-free in hci_enhanced_setup_sync+0xda5/0xdf0
Read of size 1 at addr ffff888102204047 by task kworker/u17:0/93
Call Trace:
hci_enhanced_setup_sync+0xda5/0xdf0
hci_cmd_sync_work+0x13c/0x290
process_one_work+0x6b4/0x10e0
Allocated by task 92:
__hci_conn_add+0x304/0x1df0
hci_connect_acl+0x349/0x3e0
hci_connect_sco+0x3b/0x9a0
sco_sock_connect+0x475/0xca0
Freed by task 94:
kfree+0x121/0x3c0
bt_link_release+0x79/0xa0
device_release+0xc8/0x240
kobject_put+0x14d/0x280
hci_conn_del+0x524/0xe30
hci_disconn_complete_evt+0x403/0x8c0
hci_event_packet+0x71b/0xb20
hci_rx_work+0x293/0x730
The accessed address is 71 bytes into the freed ACL parent, at its
features[0][3] byte; the queued SCO child is a different object. The
diagnostic preserves the loaded parent across the delay, matching the
unmodified compiled capability check, and does not change the parent
references or teardown path.
Hold hci_dev_lock() across the codec switch, including every call to
find_next_esco_param(), and release it on all selection errors. Keep
configure_datapath_sync() outside the critical section because it waits
for HCI events. Preserve parameter selection and existing return values.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Sun, 18 Oct 2026 19:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-416 |
Sun, 18 Oct 2026 16:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_conn: Lock parent access during enhanced SCO setup Bluetooth: hci_conn: Lock parent access during enhanced SCO setup hci_enhanced_setup_sync() runs on the request workqueue without the hci_dev_lock held by its caller when setup was queued. Its CVSD capability check and find_next_esco_param() dereference conn->parent while the receive workqueue can unlink and release that parent. The following interleaving can cause a use-after-free: hci_enhanced_setup_sync() hci_disconn_complete_evt() load conn->parent hci_dev_lock() hci_conn_del(ACL parent) unlink SCO child drop link's parent reference clear child->parent release ACL parent bt_link_release() kfree(parent) hci_dev_unlock() read parent->features[0][3] The reference held for the queued SCO child does not keep its ACL parent alive after unlinking. Commit 42de40abe25d ("Bluetooth: hci_conn: fix the SCO setup context lifetime") protects the child stored in the queued context, but leaves these parent accesses unprotected. With a 40 ms diagnostic delay after loading conn->parent, an instrumented kernel based on fd179f8a05be, which already contains 42de40abe25d, BUG: KASAN: slab-use-after-free in hci_enhanced_setup_sync+0xda5/0xdf0 Read of size 1 at addr ffff888102204047 by task kworker/u17:0/93 Call Trace: hci_enhanced_setup_sync+0xda5/0xdf0 hci_cmd_sync_work+0x13c/0x290 process_one_work+0x6b4/0x10e0 Allocated by task 92: __hci_conn_add+0x304/0x1df0 hci_connect_acl+0x349/0x3e0 hci_connect_sco+0x3b/0x9a0 sco_sock_connect+0x475/0xca0 Freed by task 94: kfree+0x121/0x3c0 bt_link_release+0x79/0xa0 device_release+0xc8/0x240 kobject_put+0x14d/0x280 hci_conn_del+0x524/0xe30 hci_disconn_complete_evt+0x403/0x8c0 hci_event_packet+0x71b/0xb20 hci_rx_work+0x293/0x730 The accessed address is 71 bytes into the freed ACL parent, at its features[0][3] byte; the queued SCO child is a different object. The diagnostic preserves the loaded parent across the delay, matching the unmodified compiled capability check, and does not change the parent references or teardown path. Hold hci_dev_lock() across the codec switch, including every call to find_next_esco_param(), and release it on all selection errors. Keep configure_datapath_sync() outside the critical section because it waits for HCI events. Preserve parameter selection and existing return values. | |
| Title | Bluetooth: hci_conn: Lock parent access during enhanced SCO setup | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-10-19T09:24:46.628Z
Reserved: 2026-09-25T10:25:14.367Z
Link: CVE-2026-98736
No data.
Status : Received
Published: 2026-10-18T16:17:27.237
Modified: 2026-10-19T10:19:37.737
Link: CVE-2026-98736
No data.
OpenCVE Enrichment
Updated: 2026-10-19T10:45:16Z
Weaknesses