[PATCH 3/7] audit: eliminate string copy for new tree rules

[Richard Guy Briggs]

New tree rules copy the path twice and discard the intermediary copy.

This saves one pointer at the expense of one path string copy.

Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
---
 kernel/audit_tree.c  |    9 +++++----
 kernel/auditfilter.c |    5 +++--
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index bd418c4..ace72ed 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -17,7 +17,7 @@ struct audit_tree {
 	struct list_head list;
 	struct list_head same_root;
 	struct rcu_head head;
-	char pathname[];
+	char *pathname;
 };
 
 struct audit_chunk {
@@ -70,11 +70,11 @@ static LIST_HEAD(prune_list);
 
 static struct fsnotify_group *audit_tree_group;
 
-static struct audit_tree *alloc_tree(const char *s)
+static struct audit_tree *alloc_tree(char *s)
 {
 	struct audit_tree *tree;
 
-	tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
+	tree = kmalloc(sizeof(struct audit_tree), GFP_KERNEL);
 	if (tree) {
 		atomic_set(&tree->count, 1);
 		tree->goner = 0;
@@ -83,7 +83,7 @@ static struct audit_tree *alloc_tree(const char *s)
 		INIT_LIST_HEAD(&tree->list);
 		INIT_LIST_HEAD(&tree->same_root);
 		tree->root = NULL;
-		strcpy(tree->pathname, s);
+		tree->pathname = s;
 	}
 	return tree;
 }
@@ -96,6 +96,7 @@ static inline void get_tree(struct audit_tree *tree)
 static inline void put_tree(struct audit_tree *tree)
 {
 	if (atomic_dec_and_test(&tree->count))
+		kfree(tree->pathname);
 		kfree_rcu(tree, head);
 }
 
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index e3378a4..facd704 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -534,9 +534,10 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
 			entry->rule.buflen += f->val;
 
 			err = audit_make_tree(&entry->rule, str, f->op);
-			kfree(str);
-			if (err)
+			if (err) {
+				kfree(str);
 				goto exit_free;
+			}
 			break;
 		case AUDIT_INODE:
 			err = audit_to_inode(&entry->rule, f);
-- 
1.7.1