scsi: target: consistently null-terminate t10_wwn strings

In preparation for supporting user provided vendor strings, add an extra
byte to the vendor, model and revision arrays in struct t10_wwn. This
ensures that the full INQUIRY data can be carried in the arrays along with
a null-terminator.

Change a number of array readers and writers so that they account for
explicit null-termination:

- The pscsi_set_inquiry_info() and emulate_model_alias_store() codepaths
  don't currently explicitly null-terminate; fix this.

- Existing t10_wwn field dumps use for-loops which step over
  null-terminators for right-padding.
  + Use printf with width specifiers instead.

Signed-off-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 11 insertions, 5 deletions

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 0e8449be5115..aaf2a785e225 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -620,12 +620,17 @@ static void dev_set_t10_wwn_model_alias(struct se_device *dev)
 	const char *configname;
 
 	configname = config_item_name(&dev->dev_group.cg_item);
-	if (strlen(configname) >= 16) {
+	if (strlen(configname) >= INQUIRY_MODEL_LEN) {
 		pr_warn("dev[%p]: Backstore name '%s' is too long for "
-			"INQUIRY_MODEL, truncating to 16 bytes\n", dev,
+			"INQUIRY_MODEL, truncating to 15 characters\n", dev,
 			configname);
 	}
-	snprintf(&dev->t10_wwn.model[0], 16, "%s", configname);
+	/*
+	 * XXX We can't use sizeof(dev->t10_wwn.model) (INQUIRY_MODEL_LEN + 1)
+	 * here without potentially breaking existing setups, so continue to
+	 * truncate one byte shorter than what can be carried in INQUIRY.
+	 */
+	strlcpy(dev->t10_wwn.model, configname, INQUIRY_MODEL_LEN);
 }
 
 static ssize_t emulate_model_alias_store(struct config_item *item,
@@ -647,11 +652,12 @@ static ssize_t emulate_model_alias_store(struct config_item *item,
 	if (ret < 0)
 		return ret;
 
+	BUILD_BUG_ON(sizeof(dev->t10_wwn.model) != INQUIRY_MODEL_LEN + 1);
 	if (flag) {
 		dev_set_t10_wwn_model_alias(dev);
 	} else {
-		strncpy(&dev->t10_wwn.model[0],
-			dev->transport->inquiry_prod, 16);
+		strlcpy(dev->t10_wwn.model, dev->transport->inquiry_prod,
+			sizeof(dev->t10_wwn.model));
 	}
 	da->emulate_model_alias = flag;
 	return count;