diff --git a/net/netfilter/xt_SECMARK.c b/net/netfilter/xt_SECMARK.c
index c2ce9c4..de9537a 100644
--- a/net/netfilter/xt_SECMARK.c
+++ b/net/netfilter/xt_SECMARK.c
@@ -57,6 +57,8 @@ static int checkentry_selinux(struct xt_secmark_target_info *info)
 {
 	int err;
 	struct xt_secmark_target_selinux_info *sel = &info->u.sel;
+	
+	sel->selctx[SECMARK_SELCTX_MAX - 1] = '\0';
 
 	err = selinux_string_to_sid(sel->selctx, &sel->selsid);
 	if (err) {