smatch_param_cleared.c

   1 /*
   2  * sparse/smatch_param_cleared.c
   3  *
   4  * Copyright (C) 2012 Oracle.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * This works together with smatch_clear_buffer.c.  This one is only for
  12  * tracking the information and smatch_clear_buffer.c changes SMATCH_EXTRA.
  13  *
  14  * This tracks functions like memset() which clear out a chunk of memory.
  15  * It fills in a gap that smatch_param_set.c can't handle.  It only handles
  16  * void pointers because smatch_param_set.c should handle the rest.
  17  */
  18
  19 #include "scope.h"
  20 #include "smatch.h"
  21 #include "smatch_slist.h"
  22 #include "smatch_extra.h"
  23
  24 static int my_id;
  25
  26 STATE(cleared);
  27 STATE(zeroed);
  28
  29 static void db_param_cleared(struct expression *expr, int param, char *key, char *value)
  30 {
  31         struct expression *arg;
  32
  33         while (expr->type == EXPR_ASSIGNMENT)
  34                 expr = strip_expr(expr->right);
  35         if (expr->type != EXPR_CALL)
  36                 return;
  37
  38         arg = get_argument_from_call_expr(expr->args, param);
  39         arg = strip_expr(arg);
  40         if (!arg)
  41                 return;
  42         if (arg->type != EXPR_SYMBOL)
  43                 return;
  44         if (get_param_num_from_sym(arg->symbol) < 0)
  45                 return;
  46
  47         if (strcmp(value, "0") == 0)
  48                 set_state_expr(my_id, arg, &zeroed);
  49         else
  50                 set_state_expr(my_id, arg, &cleared);
  51 }
  52
  53 static void match_memset(const char *fn, struct expression *expr, void *arg)
  54 {
  55         db_param_cleared(expr, PTR_INT(arg), (char *)"$$", (char *)"0");
  56 }
  57
  58 static void match_memcpy(const char *fn, struct expression *expr, void *arg)
  59 {
  60         db_param_cleared(expr, PTR_INT(arg), (char *)"$$", (char *)"");
  61 }
  62
  63 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr, struct state_list *slist)
  64 {
  65         struct state_list *my_slist;
  66         struct sm_state *sm;
  67         int param;
  68
  69         my_slist = get_all_states_slist(my_id, slist);
  70
  71         FOR_EACH_PTR(my_slist, sm) {
  72                 param = get_param_num_from_sym(sm->sym);
  73                 if (param < 0)
  74                         continue;
  75
  76                 if (sm->state == &zeroed) {
  77                         sql_insert_return_states(return_id, return_ranges,
  78                                                  PARAM_CLEARED, param, "$$", "0");
  79                 }
  80
  81                 if (sm->state == &cleared) {
  82                         sql_insert_return_states(return_id, return_ranges,
  83                                                  PARAM_CLEARED, param, "$$", "");
  84                 }
  85         } END_FOR_EACH_PTR(sm);
  86 }
  87
  88 static void register_clears_param(void)
  89 {
  90         struct token *token;
  91         char name[256];
  92         const char *function;
  93         int param;
  94
  95         if (option_project == PROJ_NONE)
  96                 return;
  97
  98         snprintf(name, 256, "%s.clears_argument", option_project_str);
  99
 100         token = get_tokens_file(name);
 101         if (!token)
 102                 return;
 103         if (token_type(token) != TOKEN_STREAMBEGIN)
 104                 return;
 105         token = token->next;
 106         while (token_type(token) != TOKEN_STREAMEND) {
 107                 if (token_type(token) != TOKEN_IDENT)
 108                         return;
 109                 function = show_ident(token->ident);
 110                 token = token->next;
 111                 if (token_type(token) != TOKEN_NUMBER)
 112                         return;
 113                 param = atoi(token->number);
 114                 add_function_hook(function, &match_memcpy, INT_PTR(param));
 115                 token = token->next;
 116         }
 117         clear_token_alloc();
 118 }
 119
 120 #define USB_DIR_IN 0x80
 121 static void match_usb_control_msg(const char *fn, struct expression *expr, void *_size_arg)
 122 {
 123         struct expression *inout;
 124         sval_t sval;
 125
 126         inout = get_argument_from_call_expr(expr->args, 3);
 127
 128         if (get_value(inout, &sval) && !(sval.uvalue & USB_DIR_IN))
 129                 return;
 130
 131         db_param_cleared(expr, 6, (char *)"$$", (char *)"");
 132 }
 133
 134 void register_param_cleared(int id)
 135 {
 136         if (!option_info)
 137                 return;
 138
 139         my_id = id;
 140
 141         add_function_hook("memset", &match_memset, INT_PTR(0));
 142
 143         add_function_hook("memcpy", &match_memcpy, INT_PTR(0));
 144         add_function_hook("memmove", &match_memcpy, INT_PTR(0));
 145         register_clears_param();
 146
 147         add_db_return_states_callback(PARAM_CLEARED, &db_param_cleared);
 148         add_returned_state_callback(&print_return_value_param);
 149
 150         if (option_project == PROJ_KERNEL) {
 151                 add_function_hook("usb_control_msg", &match_usb_control_msg, NULL);
 152         }
 153
 154 }
 155