diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index c6921a0..3be30c7 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -529,7 +529,7 @@
 	if (!*args)
 		goto out;
 
-	arg_size = size - (args - (char *) value);
+	arg_size = size - (args - (largs ? largs : (char *) value));
 	if (strcmp(name, "current") == 0) {
 		if (strcmp(command, "changehat") == 0) {
 			error = aa_setprocattr_changehat(args, arg_size,