audit: fix a memory leak bug

In audit_rule_change(), audit_data_to_entry() is firstly invoked to
translate the payload data to the kernel's rule representation. In
audit_data_to_entry(), depending on the audit field type, an audit tree may
be created in audit_make_tree(), which eventually invokes kmalloc() to
allocate the tree.  Since this tree is a temporary tree, it will be then
freed in the following execution, e.g., audit_add_rule() if the message
type is AUDIT_ADD_RULE or audit_del_rule() if the message type is
AUDIT_DEL_RULE. However, if the message type is neither AUDIT_ADD_RULE nor
AUDIT_DEL_RULE, i.e., the default case of the switch statement, this
temporary tree is not freed.

To fix this issue, only allocate the tree when the type is AUDIT_ADD_RULE
or AUDIT_DEL_RULE.

Signed-off-by: Wenwen Wang <wang6495@umn.edu>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

1 files changed, 7 insertions, 5 deletions

diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 2c3c2f349b23..1bc6410413e6 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1114,22 +1114,24 @@ int audit_rule_change(int type, int seq, void *data, size_t datasz)
         int err = 0;
         struct audit_entry *entry;
 
-        entry = audit_data_to_entry(data, datasz);
-        if (IS_ERR(entry))
-                return PTR_ERR(entry);
-
         switch (type) {
         case AUDIT_ADD_RULE:
+                entry = audit_data_to_entry(data, datasz);
+                if (IS_ERR(entry))
+                        return PTR_ERR(entry);
                 err = audit_add_rule(entry);
                 audit_log_rule_change("add_rule", &entry->rule, !err);
                 break;
         case AUDIT_DEL_RULE:
+                entry = audit_data_to_entry(data, datasz);
+                if (IS_ERR(entry))
+                        return PTR_ERR(entry);
                 err = audit_del_rule(entry);
                 audit_log_rule_change("remove_rule", &entry->rule, !err);
                 break;
         default:
-                err = -EINVAL;
                 WARN_ON(1);
+                return -EINVAL;
         }
 
         if (err || type == AUDIT_DEL_RULE) {