nvmet: do not allow model_number exceed 40 bytes

According to the NVM specifications, the model number size should be
40 bytes (bytes 63:24 of the Identify Controller data structure).
Therefore, any attempt to store a value into model_number which
exceeds 40 bytes should return an error.
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Noam Gottlieb <ngottlieb@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/configfs.c

@@ -1149,6 +1149,12 @@ static ssize_t nvmet_subsys_attr_model_store_locked(struct nvmet_subsys *subsys,
 	if (!len)
 		return -EINVAL;
 
+	if (len > NVMET_MN_MAX_SIZE) {
+		pr_err("Model nubmer size can not exceed %d Bytes\n",
+		       NVMET_MN_MAX_SIZE);
+		return -EINVAL;
+	}
+
 	for (pos = 0; pos < len; pos++) {
 		if (!nvmet_is_ascii(page[pos]))
 			return -EINVAL;

drivers/nvme/target/nvmet.h

@@ -27,6 +27,7 @@
 #define NVMET_ERROR_LOG_SLOTS		128
 #define NVMET_NO_ERROR_LOC		((u16)-1)
 #define NVMET_DEFAULT_CTRL_MODEL	"Linux"
+#define NVMET_MN_MAX_SIZE		40
 
 /*
  * Supported optional AENs: