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

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.

Fixes: e29c47fe8946 ("scsi: pm8001: Simplify pm8001_task_exec()")
Signed-off-by: Salomon Dushimirimana <salomondush@google.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://patch.msgid.link/20260213192806.439432-1-salomondush@google.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>