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

Commit e29c47f ("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: e29c47f ("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>

Author: Salomon Dushimirimana

drivers/scsi/pm8001/pm8001_sas.c

@@ -525,8 +525,9 @@ int pm8001_queue_command(struct sas_task *task, gfp_t gfp_flags)
 		} else {
 			task->task_done(task);
 		}
-		rc = -ENODEV;
-		goto err_out;
+		spin_unlock_irqrestore(&pm8001_ha->lock, flags);
+		pm8001_dbg(pm8001_ha, IO, "pm8001_task_exec device gone\n");
+		return 0;
 	}
 
 	ccb = pm8001_ccb_alloc(pm8001_ha, pm8001_dev, task);