CVE-2026-98809
Description
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister
hci_unregister_dev() disables cmd_work and cmd_timer, then calls
hci_cmd_sync_clear(), whose cancel_work_sync() waits for
hci_cmd_sync_work() to return. That worker dequeues and runs every
entry on cmd_sync_work_list. With cmd_work disabled nothing reaches
the controller, so each queued HCI command waits the full
HCI_CMD_TIMEOUT (2s).
The backlog has no bound. Userspace can keep queuing MGMT commands
such as MGMT_OP_GET_CLOCK_INFO against a controller that doesn't
answer. Closing /dev/vhci then blocks in vhci_release() for
backlog * 2s:
INFO: task syz-executor:5749 blocked for more than 143 seconds.
cancel_work_sync
hci_cmd_sync_clear
hci_unregister_dev
vhci_release
In a local reproduction the backlog held more than 5000 entries,
which comes to hours of hang.
Stop the worker from taking new entries once HCI_UNREGISTER is set,
and wake any request still waiting with -ENODEV before cancelling
the work. The entries left over are destroyed with -ECANCELED by the
existing sweep in hci_cmd_sync_clear(). They stay on the list until
the work has stopped, so hci_cmd_sync_dequeue() and friends still see
them. A callback already running may still issue another command,
which delays unregister by at most one timeout per remaining command,
not by the whole backlog.
EPSS (Exploit Prediction Scoring System)
EPSS (Exploit Prediction Scoring System)
Prevede la probabilità di sfruttamento basata su intelligence sulle minacce e sulle caratteristiche della vulnerabilità.