scsi: pm8001: Fix use-after-free in pm8001_queue_command()

In the Linux kernel, the following vulnerability has been resolved:

scsi: pm8001: Fix use-after-free in pm8001_queue_command()

Commit e29c47fe8946 ("scsi: pm8001: Simplify pm8001_task_exec()") refactors

pm8001_queue_command(), however it introduces a potential cause of a double

free scenario when it changes the function to return -ENODEV in case of phy

down/device gone state.

In this path, pm8001_queue_command() updates task status and calls

task_done to indicate to upper layer that the task has been handled.

However, this also frees the underlying SAS task. A -ENODEV is then

returned to the caller. When libsas sas_ata_qc_issue() receives this error

value, it assumes the task wasn't handled/queued by LLDD and proceeds to

clean up and free the task again, resulting in a double free.

Since pm8001_queue_command() handles the SAS task in this case, it should

return 0 to the caller indicating that the task has been handled.