check_list_add.c

   1 /*
   2  * Copyright (C) 2020 Oracle.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 /*
  19  * This is the "strict" version which is more daring and ambitious than
  20  * the check_free.c file.  The difference is that this looks at split
  21  * returns and the other only looks at if every path frees a parameter.
  22  * Also this has a bunch of kernel specific things to do with reference
  23  * counted memory.
  24  */
  25
  26 #include <string.h>
  27 #include "smatch.h"
  28 #include "smatch_slist.h"
  29 #include "smatch_extra.h"
  30
  31 static int my_id;
  32 static int next_id;
  33
  34 STATE(added);
  35 STATE(trigger);
  36
  37 static unsigned long silenced;
  38
  39 static void set_ignore(struct sm_state *sm, struct expression *mod_expr)
  40 {
  41         set_state(my_id, sm->name, sm->sym, &undefined);
  42 }
  43
  44 struct statement *ignored_stmt;
  45 static void trigger_list_del(struct sm_state *sm, struct expression *mod_expr)
  46 {
  47         char buf[64];
  48         char *p;
  49
  50         if (__cur_stmt == ignored_stmt)
  51                 return;
  52
  53         snprintf(buf, sizeof(buf), "&%s", sm->name);
  54         p = strstr(buf, ".next");
  55         if (!p)
  56                 return;
  57         *p = '\0';
  58         set_state(my_id, buf, sm->sym, &undefined);
  59 }
  60
  61 static void set_up_next_trigger(struct expression *expr)
  62 {
  63         struct symbol *type, *member;
  64         struct expression *next;
  65
  66         type = get_pointer_type(expr);
  67         if (!type || type->type != SYM_STRUCT)
  68                 return;
  69         member = first_ptr_list((struct ptr_list *)type->symbol_list);
  70         if (!member || !member->ident ||
  71             strcmp(member->ident->name, "next") != 0)
  72                 return;
  73
  74         if (expr->type == EXPR_PREOP && expr->op == '&')
  75                 expr = expr->unop;
  76
  77         next = member_expression(expr, '.', member->ident);
  78         set_state_expr(next_id, next, &trigger);
  79         ignored_stmt = __cur_stmt;
  80 }
  81
  82 static void match_add(const char *fn, struct expression *expr, void *param)
  83 {
  84         struct expression *arg;
  85
  86         arg = get_argument_from_call_expr(expr->args, 0);
  87         set_state_expr(my_id, arg, &added);
  88         set_up_next_trigger(arg);
  89 }
  90
  91 static void match_del(const char *fn, struct expression *expr, void *param)
  92 {
  93         struct expression *arg;
  94
  95         arg = get_argument_from_call_expr(expr->args, 0);
  96         if (!get_state_expr(my_id, arg)) {
  97                 silenced = true;
  98                 return;
  99         }
 100         set_state_expr(my_id, arg, &undefined);
 101 }
 102
 103 static void match_free(const char *fn, struct expression *expr, void *param)
 104 {
 105         struct expression *arg;
 106         struct sm_state *sm;
 107         char *name;
 108         struct symbol *sym;
 109
 110         if (silenced)
 111                 return;
 112
 113         arg = get_argument_from_call_expr(expr->args, PTR_INT(param));
 114         if (!arg)
 115                 return;
 116         name = expr_to_var_sym(arg, &sym);
 117         if (!name || !sym)
 118                 goto free;
 119
 120         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 121                 if (sm->state == &undefined)
 122                         continue;
 123                 if (sm->sym != sym)
 124                         continue;
 125                 if (strncmp(sm->name + 1, name, strlen(name)) != 0)
 126                         continue;
 127                 sm_warning("'%s' not removed from list", sm->name);
 128                 goto free;
 129         } END_FOR_EACH_SM(sm);
 130 free:
 131         free_string(name);
 132 }
 133
 134 void check_list_add(int id)
 135 {
 136         my_id = id;
 137
 138         if (option_project != PROJ_KERNEL)
 139                 return;
 140
 141         add_function_data(&silenced);
 142
 143         add_function_hook("list_add", &match_add, NULL);
 144         add_function_hook("list_add_tail", &match_add, NULL);
 145         add_function_hook("list_del", &match_del, NULL);
 146
 147         add_modification_hook(my_id, &set_ignore);
 148
 149         add_function_hook("kfree", &match_free, 0);
 150 }
 151
 152 void check_list_add_late(int id)
 153 {
 154         next_id = id;
 155         add_modification_hook(next_id, &trigger_list_del);
 156 }