scsi: scsi_debug: num_tgts must be >= 0

Passing the parameter "num_tgts=-1" will start an infinite loop that
exhausts the system memory

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Maurizio Lombardi <[email protected]>
Acked-by: Douglas Gilbert <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: maurizio-lombardi

drivers/scsi/scsi_debug.c

@@ -5263,6 +5263,11 @@ static int __init scsi_debug_init(void)
 		return -EINVAL;
 	}
 
+	if (sdebug_num_tgts < 0) {
+		pr_err("num_tgts must be >= 0\n");
+		return -EINVAL;
+	}
+
 	if (sdebug_guard > 1) {
 		pr_err("guard must be 0 or 1\n");
 		return -EINVAL;