In the Linux kernel, the following vulnerability has been resolved:
scsi: core: Run queues for all non-SDEV_DEL devices from scsi_run_host_queues
While a SCSI host is in a recovery state, scsi_mq_requeue_cmd() will not
set the requeue list for a requeued command to be kicked in the future.
The expectation is a call to scsi_run_host_queues() will kick all SCSI
devices once the recovery state is cleared.
However, scsi_run_host_queues() uses shost_for_each_device() which uses
scsi_device_get() and so will ignore devices in a partially removed
state like SDEV_CANCEL. But these devices may also have requeued
requests, leaving their requests stuck from not being kicked and causing
the removal process of the device to hang.
scsi_run_host_queues() needs to run against more devices than the macro
shost_for_each_device() allows. Instead of using the too limiting
scsi_device_get() state checks, only ignore devices in SDEV_DEL state or
when unable to acquire a reference. Attempt to run the queues for all
other devices when scsi_run_host_queues() is called.
