smatch_param_cleared.c

   1 /*
   2  * Copyright (C) 2012 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 works together with smatch_clear_buffer.c.  This one is only for
  20  * tracking the information and smatch_clear_buffer.c changes SMATCH_EXTRA.
  21  *
  22  * This tracks functions like memset() which clear out a chunk of memory.
  23  * It fills in a gap that smatch_param_set.c can't handle.  It only handles
  24  * void pointers because smatch_param_set.c should handle the rest.  Oh.  And
  25  * also it handles arrays because Smatch sucks at handling arrays.
  26  */
  27
  28 #include "scope.h"
  29 #include "smatch.h"
  30 #include "smatch_slist.h"
  31 #include "smatch_extra.h"
  32
  33 static int my_id;
  34
  35 STATE(cleared);
  36 STATE(zeroed);
  37
  38 static void db_param_cleared(struct expression *expr, int param, char *key, char *value)
  39 {
  40         struct expression *arg;
  41         char *name;
  42         struct symbol *sym;
  43
  44         while (expr->type == EXPR_ASSIGNMENT)
  45                 expr = strip_expr(expr->right);
  46         if (expr->type != EXPR_CALL)
  47                 return;
  48
  49         arg = get_argument_from_call_expr(expr->args, param);
  50         name = get_variable_from_key(arg, key, &sym);
  51         if (!name || !sym)
  52                 goto free;
  53
  54         if (strcmp(value, "0") == 0)
  55                 set_state(my_id, name, sym, &zeroed);
  56         else
  57                 set_state(my_id, name, sym, &cleared);
  58 free:
  59         free_string(name);
  60 }
  61
  62 static void match_memset(const char *fn, struct expression *expr, void *arg)
  63 {
  64         db_param_cleared(expr, PTR_INT(arg), (char *)"$", (char *)"0");
  65 }
  66
  67 static void match_memcpy(const char *fn, struct expression *expr, void *arg)
  68 {
  69         db_param_cleared(expr, PTR_INT(arg), (char *)"$", (char *)"");
  70 }
  71
  72 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
  73 {
  74         struct stree *stree;
  75         struct sm_state *sm;
  76         int param;
  77         const char *param_name;
  78
  79         stree = __get_cur_stree();
  80
  81         FOR_EACH_MY_SM(my_id, stree, sm) {
  82                 param = get_param_num_from_sym(sm->sym);
  83                 if (param < 0)
  84                         continue;
  85
  86                 param_name = get_param_name(sm);
  87                 if (!param_name)
  88                         continue;
  89
  90                 if (sm->state == &zeroed) {
  91                         sql_insert_return_states(return_id, return_ranges,
  92                                                  PARAM_CLEARED, param, param_name, "0");
  93                 }
  94
  95                 if (sm->state == &cleared) {
  96                         sql_insert_return_states(return_id, return_ranges,
  97                                                  PARAM_CLEARED, param, param_name, "");
  98                 }
  99         } END_FOR_EACH_SM(sm);
 100 }
 101
 102 static void register_clears_param(void)
 103 {
 104         struct token *token;
 105         char name[256];
 106         const char *function;
 107         int param;
 108
 109         if (option_project == PROJ_NONE)
 110                 return;
 111
 112         snprintf(name, 256, "%s.clears_argument", option_project_str);
 113
 114         token = get_tokens_file(name);
 115         if (!token)
 116                 return;
 117         if (token_type(token) != TOKEN_STREAMBEGIN)
 118                 return;
 119         token = token->next;
 120         while (token_type(token) != TOKEN_STREAMEND) {
 121                 if (token_type(token) != TOKEN_IDENT)
 122                         return;
 123                 function = show_ident(token->ident);
 124                 token = token->next;
 125                 if (token_type(token) != TOKEN_NUMBER)
 126                         return;
 127                 param = atoi(token->number);
 128                 add_function_hook(function, &match_memcpy, INT_PTR(param));
 129                 token = token->next;
 130         }
 131         clear_token_alloc();
 132 }
 133
 134 #define USB_DIR_IN 0x80
 135 static void match_usb_control_msg(const char *fn, struct expression *expr, void *_size_arg)
 136 {
 137         struct expression *inout;
 138         sval_t sval;
 139
 140         inout = get_argument_from_call_expr(expr->args, 3);
 141
 142         if (get_value(inout, &sval) && !(sval.uvalue & USB_DIR_IN))
 143                 return;
 144
 145         db_param_cleared(expr, 6, (char *)"$", (char *)"");
 146 }
 147
 148 static void match_assign(struct expression *expr)
 149 {
 150         struct symbol *type;
 151
 152         /*
 153          * If we have struct foo x, y; and we say that x = y; then it
 154          * initializes the struct holes.  So we record that here.
 155          */
 156         type = get_type(expr->left);
 157         if (!type || type->type != SYM_STRUCT)
 158                 return;
 159         set_state_expr(my_id, expr->left, &cleared);
 160 }
 161
 162 static void match_array_assign(struct expression *expr)
 163 {
 164         struct expression *array_expr;
 165
 166         if (!is_array(expr->left))
 167                 return;
 168
 169         array_expr = get_array_base(expr->left);
 170         set_state_expr(my_id, array_expr, &cleared);
 171 }
 172
 173 void register_param_cleared(int id)
 174 {
 175         my_id = id;
 176
 177         add_function_hook("memset", &match_memset, INT_PTR(0));
 178         add_function_hook("memzero", &match_memset, INT_PTR(0));
 179         add_function_hook("__memset", &match_memset, INT_PTR(0));
 180         add_function_hook("__memzero", &match_memset, INT_PTR(0));
 181
 182         add_function_hook("memcpy", &match_memcpy, INT_PTR(0));
 183         add_function_hook("memmove", &match_memcpy, INT_PTR(0));
 184         add_function_hook("__memcpy", &match_memcpy, INT_PTR(0));
 185         add_function_hook("__memmove", &match_memcpy, INT_PTR(0));
 186         add_function_hook("strcpy", &match_memcpy, INT_PTR(0));
 187         add_function_hook("strncpy", &match_memcpy, INT_PTR(0));
 188         add_function_hook("sprintf", &match_memcpy, INT_PTR(0));
 189         add_function_hook("snprintf", &match_memcpy, INT_PTR(0));
 190
 191         add_hook(&match_assign, ASSIGNMENT_HOOK);
 192         add_hook(&match_array_assign, ASSIGNMENT_HOOK);
 193
 194         register_clears_param();
 195
 196         select_return_states_hook(PARAM_CLEARED, &db_param_cleared);
 197         add_split_return_callback(&print_return_value_param);
 198
 199         if (option_project == PROJ_KERNEL) {
 200                 add_function_hook("usb_control_msg", &match_usb_control_msg, NULL);
 201         }
 202
 203 }
 204