--- /dev/null	Fri Dec 21 15:00:02 2018
+++ new/usr/src/tools/smatch/src/check_check_deref.c	Fri Dec 21 15:00:02 2018
@@ -0,0 +1,168 @@
+/*
+ * Copyright (C) 2010 Dan Carpenter.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
+ */
+
+/*
+ * This is like check_deref_check.c except that it complains about code like:
+ * if (a)
+ *        a->foo = 42;
+ * a->bar = 7;
+ *
+ * Of course, Smatch has complained about these for forever but the problem is
+ * the old scripts were too messy and complicated and generated too many false
+ * positives.
+ *
+ * This check is supposed to be simpler because it only looks for one kind of 
+ * null dereference bug instead of every kind.  It also gets rid of the false 
+ * positives caused by the checks that happen inside macros.
+ *
+ */
+
+#include "smatch.h"
+#include "smatch_slist.h"
+#include "smatch_extra.h"
+
+static int my_id;
+
+STATE(null);
+STATE(ok);
+
+static void is_ok(struct sm_state *sm, struct expression *mod_expr)
+{
+	set_state(my_id, sm->name, sm->sym, &ok);
+}
+
+static void check_dereference(struct expression *expr)
+{
+	struct sm_state *sm;
+	struct sm_state *tmp;
+
+	if (__in_fake_assign)
+		return;
+
+	expr = strip_expr(expr);
+
+	sm = get_sm_state_expr(my_id, expr);
+	if (!sm)
+		return;
+	if (is_ignored(my_id, sm->name, sm->sym))
+		return;
+	if (implied_not_equal(expr, 0))
+		return;
+
+	FOR_EACH_PTR(sm->possible, tmp) {
+		if (tmp->state == &merged)
+			continue;
+		if (tmp->state == &ok)
+			continue;
+		if (tmp->state == &null) {
+			sm_error("we previously assumed '%s' could be null (see line %d)",
+			       tmp->name, tmp->line);
+			add_ignore(my_id, sm->name, sm->sym);
+			return;
+		}
+	} END_FOR_EACH_PTR(tmp);
+}
+
+static void check_dereference_name_sym(char *name, struct symbol *sym)
+{
+	struct sm_state *sm;
+	struct sm_state *tmp;
+
+	sm = get_sm_state(my_id, name, sym);
+	if (!sm)
+		return;
+	if (is_ignored(my_id, sm->name, sm->sym))
+		return;
+	if (implied_not_equal_name_sym(name, sym, 0))
+		return;
+
+	FOR_EACH_PTR(sm->possible, tmp) {
+		if (tmp->state == &merged)
+			continue;
+		if (tmp->state == &ok)
+			continue;
+		if (tmp->state == &null) {
+			sm_error("we previously assumed '%s' could be null (see line %d)",
+			       tmp->name, tmp->line);
+			add_ignore(my_id, sm->name, sm->sym);
+			return;
+		}
+	} END_FOR_EACH_PTR(tmp);
+}
+
+static void match_dereferences(struct expression *expr)
+{
+	if (expr->type != EXPR_PREOP)
+		return;
+	check_dereference(expr->unop);
+}
+
+static void match_pointer_as_array(struct expression *expr)
+{
+	if (!is_array(expr))
+		return;
+	check_dereference(get_array_base(expr));
+}
+
+static void set_param_dereferenced(struct expression *call, struct expression *arg, char *key, char *unused)
+{
+	struct symbol *sym;
+	char *name;
+
+	name = get_variable_from_key(arg, key, &sym);
+	if (!name || !sym)
+		goto free;
+
+	check_dereference_name_sym(name, sym);
+free:
+	free_string(name);
+}
+
+static void match_condition(struct expression *expr)
+{
+	struct smatch_state *true_state = NULL;
+
+	if (get_macro_name(expr->pos))
+		return;
+
+	if (!is_pointer(expr))
+		return;
+
+	if (expr->type == EXPR_ASSIGNMENT) {
+		match_condition(expr->right);
+		match_condition(expr->left);
+	}
+
+	if (implied_not_equal(expr, 0))
+		return;
+
+	if (get_state_expr(my_id, expr))
+		true_state = &ok;
+
+	set_true_false_states_expr(my_id, expr, true_state, &null);
+}
+
+void check_check_deref(int id)
+{
+	my_id = id;
+
+	add_modification_hook(my_id, &is_ok);
+	add_hook(&match_dereferences, DEREF_HOOK);
+	add_hook(&match_pointer_as_array, OP_HOOK);
+	select_return_implies_hook(DEREFERENCE, &set_param_dereferenced);
+	add_hook(&match_condition, CONDITION_HOOK);
+}
