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 struct statement *ignored_stmt;
  40 static void trigger_list_del(struct sm_state *sm, struct expression *mod_expr)
  41 {
  42         char buf[64];
  43         char *p;
  44
  45         if (__cur_stmt == ignored_stmt)
  46                 return;
  47
  48         snprintf(buf, sizeof(buf), "&%s", sm->name);
  49         p = strstr(buf, ".next");
  50         if (!p)
  51                 return;
  52         *p = '\0';
  53         set_state(my_id, buf, sm->sym, &undefined);
  54 }
  55
  56 static void set_up_next_trigger(struct expression *expr)
  57 {
  58         struct symbol *type, *member;
  59         struct expression *next;
  60
  61         type = get_pointer_type(expr);
  62         if (!type || type->type != SYM_STRUCT)
  63                 return;
  64         member = first_ptr_list((struct ptr_list *)type->symbol_list);
  65         if (!member || !member->ident ||
  66             strcmp(member->ident->name, "next") != 0)
  67                 return;
  68
  69         if (expr->type == EXPR_PREOP && expr->op == '&')
  70                 expr = expr->unop;
  71
  72         next = member_expression(expr, '.', member->ident);
  73         set_state_expr(next_id, next, &trigger);
  74         ignored_stmt = __cur_stmt;
  75 }
  76
  77 static void match_add(const char *fn, struct expression *expr, void *param)
  78 {
  79         struct expression *arg;
  80
  81         arg = get_argument_from_call_expr(expr->args, 0);
  82         set_state_expr(my_id, arg, &added);
  83         set_up_next_trigger(arg);
  84 }
  85
  86 static void match_del(const char *fn, struct expression *expr, void *param)
  87 {
  88         struct expression *arg;
  89
  90         arg = get_argument_from_call_expr(expr->args, 0);
  91         if (!get_state_expr(my_id, arg)) {
  92                 silenced = true;
  93                 return;
  94         }
  95         set_state_expr(my_id, arg, &undefined);
  96 }
  97
  98 static void match_free(const char *fn, struct expression *expr, void *param)
  99 {
 100         struct expression *arg;
 101         struct sm_state *sm;
 102         char *name;
 103         struct symbol *sym;
 104
 105         if (silenced)
 106                 return;
 107
 108         arg = get_argument_from_call_expr(expr->args, PTR_INT(param));
 109         if (!arg)
 110                 return;
 111         name = expr_to_var_sym(arg, &sym);
 112         if (!name || !sym)
 113                 goto free;
 114
 115         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 116                 if (sm->state == &undefined)
 117                         continue;
 118                 if (sm->sym != sym)
 119                         continue;
 120                 if (strncmp(sm->name + 1, name, strlen(name)) != 0)
 121                         continue;
 122                 sm_warning("'%s' not removed from list", sm->name);
 123                 goto free;
 124         } END_FOR_EACH_SM(sm);
 125 free:
 126         free_string(name);
 127 }
 128
 129 void check_list_add(int id)
 130 {
 131         my_id = id;
 132
 133         if (option_project != PROJ_KERNEL)
 134                 return;
 135
 136         add_function_data(&silenced);
 137
 138         add_function_hook("list_add", &match_add, NULL);
 139         add_function_hook("list_add_tail", &match_add, NULL);
 140         add_function_hook("list_del", &match_del, NULL);
 141
 142         add_modification_hook(my_id, &set_undefined);
 143
 144         add_function_hook("kfree", &match_free, 0);
 145 }
 146
 147 void check_list_add_late(int id)
 148 {
 149         next_id = id;
 150         add_modification_hook(next_id, &trigger_list_del);
 151 }