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.
  25  */
  26
  27 #include "scope.h"
  28 #include "smatch.h"
  29 #include "smatch_slist.h"
  30 #include "smatch_extra.h"
  31
  32 static int my_id;
  33
  34 STATE(cleared);
  35 STATE(zeroed);
  36
  37 static void db_param_cleared(struct expression *expr, int param, char *key, char *value)
  38 {
  39         struct expression *arg;
  40
  41         while (expr->type == EXPR_ASSIGNMENT)
  42                 expr = strip_expr(expr->right);
  43         if (expr->type != EXPR_CALL)
  44                 return;
  45
  46         arg = get_argument_from_call_expr(expr->args, param);
  47         arg = strip_expr(arg);
  48         if (!arg)
  49                 return;
  50         if (arg->type != EXPR_SYMBOL)
  51                 return;
  52         if (get_param_num_from_sym(arg->symbol) < 0)
  53                 return;
  54
  55         if (strcmp(value, "0") == 0)
  56                 set_state_expr(my_id, arg, &zeroed);
  57         else
  58                 set_state_expr(my_id, arg, &cleared);
  59 }
  60
  61 static void match_memset(const char *fn, struct expression *expr, void *arg)
  62 {
  63         db_param_cleared(expr, PTR_INT(arg), (char *)"$$", (char *)"0");
  64 }
  65
  66 static void match_memcpy(const char *fn, struct expression *expr, void *arg)
  67 {
  68         db_param_cleared(expr, PTR_INT(arg), (char *)"$$", (char *)"");
  69 }
  70
  71 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
  72 {
  73         struct stree *stree;
  74         struct sm_state *sm;
  75         int param;
  76
  77         stree = __get_cur_stree();
  78
  79         FOR_EACH_MY_SM(my_id, stree, sm) {
  80                 param = get_param_num_from_sym(sm->sym);
  81                 if (param < 0)
  82                         continue;
  83
  84                 if (sm->state == &zeroed) {
  85                         sql_insert_return_states(return_id, return_ranges,
  86                                                  PARAM_CLEARED, param, "$$", "0");
  87                 }
  88
  89                 if (sm->state == &cleared) {
  90                         sql_insert_return_states(return_id, return_ranges,
  91                                                  PARAM_CLEARED, param, "$$", "");
  92                 }
  93         } END_FOR_EACH_SM(sm);
  94 }
  95
  96 static void register_clears_param(void)
  97 {
  98         struct token *token;
  99         char name[256];
 100         const char *function;
 101         int param;
 102
 103         if (option_project == PROJ_NONE)
 104                 return;
 105
 106         snprintf(name, 256, "%s.clears_argument", option_project_str);
 107
 108         token = get_tokens_file(name);
 109         if (!token)
 110                 return;
 111         if (token_type(token) != TOKEN_STREAMBEGIN)
 112                 return;
 113         token = token->next;
 114         while (token_type(token) != TOKEN_STREAMEND) {
 115                 if (token_type(token) != TOKEN_IDENT)
 116                         return;
 117                 function = show_ident(token->ident);
 118                 token = token->next;
 119                 if (token_type(token) != TOKEN_NUMBER)
 120                         return;
 121                 param = atoi(token->number);
 122                 add_function_hook(function, &match_memcpy, INT_PTR(param));
 123                 token = token->next;
 124         }
 125         clear_token_alloc();
 126 }
 127
 128 #define USB_DIR_IN 0x80
 129 static void match_usb_control_msg(const char *fn, struct expression *expr, void *_size_arg)
 130 {
 131         struct expression *inout;
 132         sval_t sval;
 133
 134         inout = get_argument_from_call_expr(expr->args, 3);
 135
 136         if (get_value(inout, &sval) && !(sval.uvalue & USB_DIR_IN))
 137                 return;
 138
 139         db_param_cleared(expr, 6, (char *)"$$", (char *)"");
 140 }
 141
 142 static void match_assign(struct expression *expr)
 143 {
 144         struct symbol *type;
 145
 146         type = get_type(expr->left);
 147         if (!type || type->type != SYM_STRUCT)
 148                 return;
 149         set_state_expr(my_id, expr->left, &cleared);
 150 }
 151
 152 void register_param_cleared(int id)
 153 {
 154         my_id = id;
 155
 156         add_function_hook("memset", &match_memset, INT_PTR(0));
 157         add_function_hook("__memzero", &match_memset, INT_PTR(0));
 158         add_function_hook("memzero", &match_memset, INT_PTR(0));
 159
 160         add_function_hook("memcpy", &match_memcpy, INT_PTR(0));
 161         add_function_hook("memmove", &match_memcpy, INT_PTR(0));
 162         add_function_hook("strcpy", &match_memcpy, INT_PTR(0));
 163         add_function_hook("strncpy", &match_memcpy, INT_PTR(0));
 164         add_function_hook("sprintf", &match_memcpy, INT_PTR(0));
 165         add_function_hook("snprintf", &match_memcpy, INT_PTR(0));
 166
 167         add_hook(&match_assign, ASSIGNMENT_HOOK);
 168
 169         register_clears_param();
 170
 171         select_return_states_hook(PARAM_CLEARED, &db_param_cleared);
 172         add_split_return_callback(&print_return_value_param);
 173
 174         if (option_project == PROJ_KERNEL) {
 175                 add_function_hook("usb_control_msg", &match_usb_control_msg, NULL);
 176         }
 177
 178 }
 179