audit: free audit_proctitle only on task exit

Since audit_proctitle is generated at syscall exit time, its value is
used immediately and cached for the next syscall.  Since this is the
case, then only clear it at task exit time.  Otherwise, there is no
point in caching the value OR bearing the overhead of regenerating it.

Fixes: 12c5e81d ("audit: prepare audit_context for use in calling contexts beyond syscalls")
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

kernel/auditsc.c

@@ -1016,7 +1016,6 @@ static void audit_reset_context(struct audit_context *ctx)
 	WARN_ON(!list_empty(&ctx->killed_trees));
 	audit_free_module(ctx);
 	ctx->fds[0] = -1;
-	audit_proctitle_free(ctx);
 	ctx->type = 0; /* reset last for audit_free_*() */
 }
 
@@ -1077,6 +1076,7 @@ static inline void audit_free_context(struct audit_context *context)
 {
 	/* resetting is extra work, but it is likely just noise */
 	audit_reset_context(context);
+	audit_proctitle_free(context);
 	free_tree_refs(context);
 	kfree(context->filterkey);
 	kfree(context);