null_blk: validate the number of devices

A negative number of devices is nonsensical, so change the type to unsigned. If the number of devices is 0, it is impossible for userspace to interact with the module, so refuse loading the driver for that case. Signed-off-by: André Almeida <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
devinus · Sep 11, 2019 · f7c4ce8 · f7c4ce8
1 parent 4e47ee8
commit f7c4ce8
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
@@ -141,7 +141,7 @@ static int g_bs = 512;
 module_param_named(bs, g_bs, int, 0444);
 MODULE_PARM_DESC(bs, "Block size (in bytes)");
 
-static int nr_devices = 1;
+static unsigned int nr_devices = 1;
 module_param(nr_devices, int, 0444);
 MODULE_PARM_DESC(nr_devices, "Number of devices to register");
 
@@ -1767,6 +1767,10 @@ static int __init null_init(void)
 		pr_err("null_blk: legacy IO path no longer available\n");
 		return -EINVAL;
 	}
+	if (!nr_devices) {
+		pr_err("null_blk: invalid number of devices\n");
+		return -EINVAL;
+	}
 	if (g_queue_mode == NULL_Q_MQ && g_use_per_node_hctx) {
 		if (g_submit_queues != nr_online_nodes) {
 			pr_warn("null_blk: submit_queues param is set to %u.\n",