ima: return dentry name if mnt is NULL

This patch returns dentry name if mnt is NULL.
Symbolic links checking hook does not have mnt.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 69acb78..a5938c8 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -329,9 +329,12 @@
 const char *ima_d_path(struct path *path, char **pathbuf)
 {
 	char *pathname = NULL;
+	struct dentry *dentry = path->dentry;
 
-	if (!path->mnt)
+	if (!dentry)
 		return NULL;
+	if (!path->mnt)
+		goto out;
 
 	/* We will allow 11 spaces for ' (deleted)' to be appended */
 	*pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
@@ -343,5 +346,6 @@
 			pathname = NULL;
 		}
 	}
-	return pathname ?: (const char *)path->dentry->d_name.name;
+out:
+	return pathname ?: (const char *)dentry->d_name.name;
 }