GHSA-JXF9-629P-PMQW
Vulnerability from github – Published: 2026-10-18 18:32 – Updated: 2026-10-30 15:33In 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.
{
"affected": [],
"aliases": [
"CVE-2026-98736"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-18T16:17:27Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_conn: Lock parent access during enhanced SCO setup\n\nBluetooth: hci_conn: Lock parent access during enhanced SCO setup\n\nhci_enhanced_setup_sync() runs on the request workqueue without the\nhci_dev_lock held by its caller when setup was queued. Its CVSD\ncapability check and find_next_esco_param() dereference conn-\u003eparent\nwhile the receive workqueue can unlink and release that parent.\n\nThe following interleaving can cause a use-after-free:\n\n hci_enhanced_setup_sync() hci_disconn_complete_evt()\n load conn-\u003eparent\n hci_dev_lock()\n hci_conn_del(ACL parent)\n unlink SCO child\n drop link\u0027s parent reference\n clear child-\u003eparent\n release ACL parent\n bt_link_release()\n kfree(parent)\n hci_dev_unlock()\n read parent-\u003efeatures[0][3]\n\nThe reference held for the queued SCO child does not keep its ACL parent\nalive after unlinking. Commit 42de40abe25d (\"Bluetooth: hci_conn: fix the\nSCO setup context lifetime\") protects the child stored in the queued\ncontext, but leaves these parent accesses unprotected.\n\nWith a 40 ms diagnostic delay after loading conn-\u003eparent, an instrumented\nkernel based on fd179f8a05be, which already contains 42de40abe25d,\n\n BUG: KASAN: slab-use-after-free in hci_enhanced_setup_sync+0xda5/0xdf0\n Read of size 1 at addr ffff888102204047 by task kworker/u17:0/93\n Call Trace:\n hci_enhanced_setup_sync+0xda5/0xdf0\n hci_cmd_sync_work+0x13c/0x290\n process_one_work+0x6b4/0x10e0\n\n Allocated by task 92:\n __hci_conn_add+0x304/0x1df0\n hci_connect_acl+0x349/0x3e0\n hci_connect_sco+0x3b/0x9a0\n sco_sock_connect+0x475/0xca0\n\n Freed by task 94:\n kfree+0x121/0x3c0\n bt_link_release+0x79/0xa0\n device_release+0xc8/0x240\n kobject_put+0x14d/0x280\n hci_conn_del+0x524/0xe30\n hci_disconn_complete_evt+0x403/0x8c0\n hci_event_packet+0x71b/0xb20\n hci_rx_work+0x293/0x730\n\nThe accessed address is 71 bytes into the freed ACL parent, at its\nfeatures[0][3] byte; the queued SCO child is a different object. The\ndiagnostic preserves the loaded parent across the delay, matching the\nunmodified compiled capability check, and does not change the parent\nreferences or teardown path.\n\nHold hci_dev_lock() across the codec switch, including every call to\nfind_next_esco_param(), and release it on all selection errors. Keep\nconfigure_datapath_sync() outside the critical section because it waits\nfor HCI events. Preserve parameter selection and existing return values.",
"id": "GHSA-jxf9-629p-pmqw",
"modified": "2026-10-30T15:33:58Z",
"published": "2026-10-18T18:32:01Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98736"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/024e05f73a4c1263d031614bc36700ec135eecb4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1239ef0fa809b5952fca679db3faa3e1c00e1dac"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/48bf3b94c7331e11eaa6c89adc054a7bc7c0382e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/70b55855eecb428d446344d827bda8725ce8b312"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/93a737e4e042f59673cd580d35214f278d7b757d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cabd58d9bb66d49d481f762ce986173db397435d"
}
],
"schema_version": "1.4.0",
"severity": []
}
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