{"id":"CVE-2026-98736","summary":"Bluetooth: hci_conn: Lock parent access during enhanced SCO setup","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's 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.","modified":"2026-10-19T02:47:16.067149469Z","published":"2026-10-18T15:47:14.076Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98736.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"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/93a737e4e042f59673cd580d35214f278d7b757d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cabd58d9bb66d49d481f762ce986173db397435d"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98736.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98736"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"e07a06b4eb417f5271d33ce2240e93c62d98b7b4"},{"fixed":"1239ef0fa809b5952fca679db3faa3e1c00e1dac"},{"fixed":"cabd58d9bb66d49d481f762ce986173db397435d"},{"fixed":"93a737e4e042f59673cd580d35214f278d7b757d"},{"fixed":"024e05f73a4c1263d031614bc36700ec135eecb4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98736.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.1.0"},{"fixed":"6.12.113"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.56"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.10"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98736.json"}}],"schema_version":"1.9.0"}