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         arg = strip_expr(arg);
  51         name = get_variable_from_key(arg, key, &sym);
  52         if (!name || !sym)
  53                 goto free;
  54
  55         if (strcmp(value, "0") == 0)
  56                 set_state(my_id, name, sym, &zeroed);
  57         else
  58                 set_state(my_id, name, sym, &cleared);
  59 free:
  60         free_string(name);
  61 }
  62
  63 static void match_memset(const char *fn, struct expression *expr, void *arg)
  64 {
  65         db_param_cleared(expr, PTR_INT(arg), (char *)"$", (char *)"0");
  66 }
  67
  68 static void match_memcpy(const char *fn, struct expression *expr, void *arg)
  69 {
  70         db_param_cleared(expr, PTR_INT(arg), (char *)"$", (char *)"");
  71 }
  72
  73 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
  74 {
  75         struct stree *stree;
  76         struct sm_state *sm;
  77         int param;
  78         const char *param_name;
  79
  80         stree = __get_cur_stree();
  81
  82         FOR_EACH_MY_SM(my_id, stree, sm) {
  83                 param = get_param_num_from_sym(sm->sym);
  84                 if (param < 0)
  85                         continue;
  86
  87                 param_name = get_param_name(sm);
  88                 if (!param_name)
  89                         continue;
  90
  91                 if (sm->state == &zeroed) {
  92                         sql_insert_return_states(return_id, return_ranges,
  93                                                  PARAM_CLEARED, param, param_name, "0");
  94                 }
  95
  96                 if (sm->state == &cleared) {
  97                         sql_insert_return_states(return_id, return_ranges,
  98                                                  PARAM_CLEARED, param, param_name, "");
  99                 }
 100         } END_FOR_EACH_SM(sm);
 101 }
 102
 103 bool parent_was_PARAM_CLEAR(const char *name, struct symbol *sym)
 104 {
 105         struct sm_state *sm;
 106         char buf[80];
 107         int len, i;
 108
 109         if (!name)
 110                 return 0;
 111
 112         len = strlen(name);
 113         if (len >= sizeof(buf))
 114                 len = sizeof(buf) - 1;
 115
 116         for (i = len - 2; i >= 1; i--) {
 117                 if (name[i] != '-' && name[i] != '.')
 118                         continue;
 119
 120                 memcpy(buf, name, i);
 121                 buf[i] = '\0';
 122                 sm = get_sm_state(my_id, buf, sym);
 123                 if (sm && sm->state == &cleared)
 124                         return true;
 125                 if (sm)
 126                         return false;
 127
 128                 buf[0] = '&';
 129                 memcpy(buf + 1, name, i);
 130                 buf[i + 1] = '\0';
 131                 sm = get_sm_state(my_id, buf, sym);
 132                 if (sm && sm->state == &cleared)
 133                         return true;
 134                 if (sm)
 135                         return false;
 136         }
 137
 138         return false;
 139 }
 140
 141 bool parent_was_PARAM_CLEAR_ZERO(const char *name, struct symbol *sym)
 142 {
 143         struct sm_state *sm;
 144         char buf[80];
 145         int len, i;
 146
 147         if (!name)
 148                 return 0;
 149
 150         len = strlen(name);
 151         if (len >= sizeof(buf))
 152                 len = sizeof(buf) - 1;
 153
 154         for (i = len - 2; i >= 1; i--) {
 155                 if (name[i] != '-' && name[i] != '.')
 156                         continue;
 157
 158                 memcpy(buf, name, i);
 159                 buf[i] = '\0';
 160                 sm = get_sm_state(my_id, buf, sym);
 161                 if (sm && sm->state == &zeroed)
 162                         return true;
 163                 if (sm)
 164                         return false;
 165
 166                 buf[0] = '&';
 167                 memcpy(buf + 1, name, i);
 168                 buf[i + 1] = '\0';
 169                 sm = get_sm_state(my_id, buf, sym);
 170                 if (sm && sm->state == &zeroed)
 171                         return true;
 172                 if (sm)
 173                         return false;
 174         }
 175
 176         return false;
 177 }
 178
 179 static void register_clears_param(void)
 180 {
 181         struct token *token;
 182         char name[256];
 183         const char *function;
 184         int param;
 185
 186         if (option_project == PROJ_NONE)
 187                 return;
 188
 189         snprintf(name, 256, "%s.clears_argument", option_project_str);
 190
 191         token = get_tokens_file(name);
 192         if (!token)
 193                 return;
 194         if (token_type(token) != TOKEN_STREAMBEGIN)
 195                 return;
 196         token = token->next;
 197         while (token_type(token) != TOKEN_STREAMEND) {
 198                 if (token_type(token) != TOKEN_IDENT)
 199                         return;
 200                 function = show_ident(token->ident);
 201                 token = token->next;
 202                 if (token_type(token) != TOKEN_NUMBER)
 203                         return;
 204                 param = atoi(token->number);
 205                 add_function_hook(function, &match_memcpy, INT_PTR(param));
 206                 token = token->next;
 207         }
 208         clear_token_alloc();
 209 }
 210
 211 #define USB_DIR_IN 0x80
 212 static void match_usb_control_msg(const char *fn, struct expression *expr, void *_size_arg)
 213 {
 214         struct expression *inout;
 215         sval_t sval;
 216
 217         inout = get_argument_from_call_expr(expr->args, 3);
 218
 219         if (get_value(inout, &sval) && !(sval.uvalue & USB_DIR_IN))
 220                 return;
 221
 222         db_param_cleared(expr, 6, (char *)"$", (char *)"");
 223 }
 224
 225 static void match_assign(struct expression *expr)
 226 {
 227         struct symbol *type;
 228
 229         /*
 230          * If we have struct foo x, y; and we say that x = y; then it
 231          * initializes the struct holes.  So we record that here.
 232          */
 233         type = get_type(expr->left);
 234         if (!type || type->type != SYM_STRUCT)
 235                 return;
 236         set_state_expr(my_id, expr->left, &cleared);
 237 }
 238
 239 static void match_array_assign(struct expression *expr)
 240 {
 241         struct expression *array_expr;
 242
 243         if (!is_array(expr->left))
 244                 return;
 245
 246         array_expr = get_array_base(expr->left);
 247         set_state_expr(my_id, array_expr, &cleared);
 248 }
 249
 250 void register_param_cleared(int id)
 251 {
 252         my_id = id;
 253
 254         add_function_hook("memset", &match_memset, INT_PTR(0));
 255         add_function_hook("memzero", &match_memset, INT_PTR(0));
 256         add_function_hook("__memset", &match_memset, INT_PTR(0));
 257         add_function_hook("__memzero", &match_memset, INT_PTR(0));
 258
 259         add_function_hook("memcpy", &match_memcpy, INT_PTR(0));
 260         add_function_hook("memmove", &match_memcpy, INT_PTR(0));
 261         add_function_hook("__memcpy", &match_memcpy, INT_PTR(0));
 262         add_function_hook("__memmove", &match_memcpy, INT_PTR(0));
 263         add_function_hook("strcpy", &match_memcpy, INT_PTR(0));
 264         add_function_hook("strncpy", &match_memcpy, INT_PTR(0));
 265         add_function_hook("sprintf", &match_memcpy, INT_PTR(0));
 266         add_function_hook("snprintf", &match_memcpy, INT_PTR(0));
 267
 268         add_hook(&match_assign, ASSIGNMENT_HOOK);
 269         add_hook(&match_array_assign, ASSIGNMENT_HOOK);
 270
 271         register_clears_param();
 272
 273         select_return_states_hook(PARAM_CLEARED, &db_param_cleared);
 274         add_split_return_callback(&print_return_value_param);
 275
 276         if (option_project == PROJ_KERNEL) {
 277                 add_function_hook("usb_control_msg", &match_usb_control_msg, NULL);
 278         }
 279
 280 }
 281