{"id":"CVE-2026-98734","title":"Bluetooth: hci_core: Serialize SCO and ISO scheduling with teardown","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_core: Serialize SCO and ISO scheduling with teardown\n\nhci_low_sent() selects a connection under RCU but drops the read lock\nbefore calculating its quota …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= bf4c63252490ba78fb833cc7acf1a5b1900c970f < 101825c09ad6b7daa6cf4c9e6b1720b13de15596","Linux >= bf4c63252490ba78fb833cc7acf1a5b1900c970f < 1681f97afdf92e8557f2f3118ddc898471b5d299","Linux >= bf4c63252490ba78fb833cc7acf1a5b1900c970f < ecdb1c66d8e14e63731c52d6fbcfa604064913c4","Linux >= bf4c63252490ba78fb833cc7acf1a5b1900c970f < 848a7a91c7f03675d3bd8db6f7721cbf9cb50e21","Linux 3.3"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:47:12.203Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98734","references":[{"url":"https://git.kernel.org/stable/c/101825c09ad6b7daa6cf4c9e6b1720b13de15596"},{"url":"https://git.kernel.org/stable/c/1681f97afdf92e8557f2f3118ddc898471b5d299"},{"url":"https://git.kernel.org/stable/c/ecdb1c66d8e14e63731c52d6fbcfa604064913c4"},{"url":"https://git.kernel.org/stable/c/848a7a91c7f03675d3bd8db6f7721cbf9cb50e21"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T16:47:32.505Z","slug":"CVE-2026-98734","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_core: Serialize SCO and ISO scheduling with teardown\n\nhci_low_sent() selects a connection under RCU but drops the read lock\nbefore calculating its quota and returning it to the scheduler. The\nconnection is then used without lifetime protection by hci_sched_iso()\nand hci_sched_sco().\n\nAfter the TX worker drops the RCU read lock, hci_abort_conn_sync() on\nhdev->req_workqueue can remove the connection from the hash, complete\nsynchronize_rcu(), purge its queues and release it. The TX worker on\nhdev->workqueue can then access the freed connection in hci_quote_sent()\nor while dequeuing packets and updating conn->sent.\n\nKASAN reported:\n\n  BUG: KASAN: slab-use-after-free in hci_low_sent+0x730/0x840\n  Workqueue: hci0 hci_tx_work\n  Call Trace:\n   hci_low_sent+0x730/0x840\n   hci_sched_iso+0x25e/0x4d0\n   hci_tx_work+0x239/0xcb0\n\n  Allocated by task 93:\n   __hci_conn_add+0x16f/0x1b40\n   hci_bind_bis+0x782/0x17b0\n   hci_connect_bis+0xa0/0x510\n   iso_sock_connect+0x589/0x1050\n\n  Freed by task 88:\n   kfree+0x131/0x3c0\n   device_release+0xc8/0x240\n   kobject_put+0x14d/0x280\n   hci_conn_del+0x55a/0xe80\n   hci_disconnect_sync+0x156/0x180\n   hci_abort_conn_sync+0x3e7/0x940\n   hci_cmd_sync_work+0x13c/0x290\n\nHold hci_dev_lock() across connection selection and transmission in both\nSCO and ISO scheduling, serializing them with connection teardown. This\nalso prevents queuing completion timestamps after the connection queues\nhave been purged. Extending RCU across transmission would be unsafe\nbecause the transmit path can sleep. Keep the ISO timeout check outside\nthe mutex since hci_link_tx_to() takes it itself.\n\nThe preceding channel fix already holds this mutex in the ACL and LE\nschedulers, which call the SCO scheduler between packets. Move the SCO\nbody to __hci_sched_sco(), assert that its caller holds the mutex, and\nuse it directly from these locked paths. Keep a locking hci_sched_sco()\nwrapper for the direct calls from hci_tx_work(). This avoids recursively\nacquiring the device mutex while preserving the scheduling order.\n\nRemove the obsolete claim that connection removal disables TX.\n\n## Affected\n\n- `Linux >= bf4c63252490ba78fb833cc7acf1a5b1900c970f < 101825c09ad6b7daa6cf4c9e6b1720b13de15596`\n- `Linux >= bf4c63252490ba78fb833cc7acf1a5b1900c970f < 1681f97afdf92e8557f2f3118ddc898471b5d299`\n- `Linux >= bf4c63252490ba78fb833cc7acf1a5b1900c970f < ecdb1c66d8e14e63731c52d6fbcfa604064913c4`\n- `Linux >= bf4c63252490ba78fb833cc7acf1a5b1900c970f < 848a7a91c7f03675d3bd8db6f7721cbf9cb50e21`\n- `Linux 3.3`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}