--- /dev/null	Fri Dec 21 15:00:02 2018
+++ new/usr/src/tools/smatch/src/check_deref.c	Fri Dec 21 15:00:02 2018
@@ -0,0 +1,296 @@
+/*
+ * 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
+ */
+
+/*
+ * There was a previous null dereference test but it was too confusing and
+ * difficult to debug.  This test is much simpler in its goals and scope.
+ *
+ * This test only complains about:
+ * 1) dereferencing uninitialized variables
+ * 2) dereferencing variables which were assigned as null.
+ * 3) dereferencing variables which were assigned a function the returns 
+ *    null.
+ *
+ * If we dereference something then we complain if any of those three
+ * are possible.
+ *
+ */
+
+#include "smatch.h"
+#include "smatch_slist.h"
+#include "smatch_extra.h"
+
+static int my_id;
+
+#define __GFP_NOFAIL 0x800
+
+STATE(null);
+STATE(ok);
+STATE(uninitialized);
+
+static struct smatch_state *alloc_my_state(const char *name)
+{
+	struct smatch_state *state;
+
+	state = __alloc_smatch_state(0);
+	state->name = name;
+	return state;
+}
+
+static struct smatch_state *unmatched_state(struct sm_state *sm)
+{
+	return &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;
+
+	expr = strip_expr(expr);
+	if (is_static(expr))
+		return;
+	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;
+	if (is_impossible_path())
+		return;
+
+	FOR_EACH_PTR(sm->possible, tmp) {
+		if (tmp->state == &merged)
+			continue;
+		if (tmp->state == &ok)
+			continue;
+		add_ignore(my_id, sm->name, sm->sym);
+		if (tmp->state == &null) {
+			if (option_spammy)
+				sm_error("potential NULL dereference '%s'.", tmp->name);
+			return;
+		}
+		if (tmp->state == &uninitialized) {
+			if (option_spammy)
+				sm_error("potentially dereferencing uninitialized '%s'.", tmp->name);
+			return;
+		}
+		sm_error("potential null dereference '%s'.  (%s returns null)",
+			tmp->name, tmp->state->name);
+		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;
+	if (is_impossible_path())
+		return;
+
+	FOR_EACH_PTR(sm->possible, tmp) {
+		if (tmp->state == &merged)
+			continue;
+		if (tmp->state == &ok)
+			continue;
+		add_ignore(my_id, sm->name, sm->sym);
+		if (tmp->state == &null) {
+			if (option_spammy)
+				sm_error("potential NULL dereference '%s'.", tmp->name);
+			return;
+		}
+		if (tmp->state == &uninitialized) {
+			if (option_spammy)
+				sm_error("potentially dereferencing uninitialized '%s'.", tmp->name);
+			return;
+		}
+		sm_error("potential null dereference '%s'.  (%s returns null)",
+			tmp->name, tmp->state->name);
+		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_declarations(struct symbol *sym)
+{
+	const char *name;
+
+	if ((get_base_type(sym))->type == SYM_ARRAY)
+		return;
+
+	if (!sym->ident)
+		return;
+	name = sym->ident->name;
+	if (!sym->initializer) {
+		set_state(my_id, name, sym, &uninitialized);
+		scoped_state(my_id, name, sym);
+	}
+}
+
+static void match_assign(struct expression *expr)
+{
+	struct statement *stmt;
+
+	if (!is_zero(expr->right))
+		return;
+
+	if (__in_fake_assign)
+		return;
+
+	FOR_EACH_PTR_REVERSE(big_statement_stack, stmt) {
+		if (stmt->type == STMT_DECLARATION)
+			return;
+		break;
+	} END_FOR_EACH_PTR_REVERSE(stmt);
+
+	set_state_expr(my_id, expr->left, &null);
+}
+
+static void match_assigns_address(struct expression *expr)
+{
+	struct expression *right;
+
+	right = strip_expr(expr->right);
+	if (right->type != EXPR_PREOP || right->op != '&')
+		return;
+	set_state_expr(my_id, right, &ok);
+}
+
+static void match_condition(struct expression *expr)
+{
+	if (expr->type == EXPR_ASSIGNMENT) {
+		match_condition(expr->right);
+		match_condition(expr->left);
+	}
+	if (!get_state_expr(my_id, expr))
+		return;
+	set_true_false_states_expr(my_id, expr, &ok, NULL);
+}
+
+static int called_with_no_fail(struct expression *call, int param)
+{
+	struct expression *arg;
+	sval_t sval;
+
+	if (param == -1)
+		return 0;
+	call = strip_expr(call);
+	if (call->type != EXPR_CALL)
+		return 0;
+	arg = get_argument_from_call_expr(call->args, param);
+	if (get_value(arg, &sval) && (sval.uvalue & __GFP_NOFAIL))
+		return 1;
+	return 0;
+}
+
+static void match_assign_returns_null(const char *fn, struct expression *expr, void *_gfp)
+{
+	struct smatch_state *state;
+	int gfp_param = PTR_INT(_gfp);
+
+	if (called_with_no_fail(expr->right, gfp_param))
+		return;
+	state = alloc_my_state(fn);
+	set_state_expr(my_id, expr->left, state);
+}
+
+static void register_allocation_funcs(void)
+{
+	struct token *token;
+	const char *func;
+	int arg;
+
+	token = get_tokens_file("kernel.allocation_funcs_gfp");
+	if (!token)
+		return;
+	if (token_type(token) != TOKEN_STREAMBEGIN)
+		return;
+	token = token->next;
+	while (token_type(token) != TOKEN_STREAMEND) {
+		if (token_type(token) != TOKEN_IDENT)
+			return;
+		func = show_ident(token->ident);
+		token = token->next;
+		if (token_type(token) == TOKEN_IDENT)
+			arg = -1;
+		else if (token_type(token) == TOKEN_NUMBER)
+			arg = atoi(token->number);
+		else
+			return;
+		add_function_assign_hook(func, &match_assign_returns_null, INT_PTR(arg));
+		token = token->next;
+	}
+	clear_token_alloc();
+}
+
+void check_deref(int id)
+{
+	my_id = id;
+
+	add_unmatched_state_hook(my_id, &unmatched_state);
+	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);
+	add_hook(&match_declarations, DECLARATION_HOOK);
+	add_hook(&match_assign, ASSIGNMENT_HOOK);
+	add_hook(&match_assigns_address, ASSIGNMENT_HOOK);
+	if (option_project == PROJ_KERNEL)
+		register_allocation_funcs();
+}
