check_zero_to_err_ptr.c

   1 /*
   2  * Copyright (C) 2013 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 #include "smatch.h"
  19 #include "smatch_extra.h"
  20 #include "smatch_slist.h"
  21
  22 static int my_id;
  23
  24 static bool is_select_assign(struct expression *expr)
  25 {
  26         /* select assignments are faked in smatch_conditions.c */
  27         expr = expr_get_parent_expr(expr);
  28         if (!expr || expr->type != EXPR_ASSIGNMENT)
  29                 return false;
  30         expr = expr_get_parent_expr(expr);
  31         if (!expr)
  32                 return false;
  33         if (expr->type == EXPR_CONDITIONAL ||
  34             expr->type == EXPR_SELECT)
  35                 return true;
  36         return false;
  37 }
  38
  39 static int is_comparison_call(struct expression *expr)
  40 {
  41         expr = expr_get_parent_expr(expr);
  42         if (!expr || expr->type != EXPR_COMPARE)
  43                 return 0;
  44         if (expr->op != SPECIAL_EQUAL && expr->op != SPECIAL_NOTEQUAL)
  45                 return 0;
  46         return 1;
  47 }
  48
  49 static bool is_switch_condition(struct expression *expr)
  50 {
  51         struct statement *stmt;
  52
  53         stmt = expr_get_parent_stmt(expr);
  54         if (stmt && stmt->type == STMT_SWITCH)
  55                 return true;
  56         return false;
  57 }
  58
  59 static bool is_condition_expr(struct expression *expr)
  60 {
  61         if (is_comparison_call(expr) ||
  62             is_select_assign(expr) ||
  63             is_switch_condition(expr))
  64                 return true;
  65         return false;
  66 }
  67
  68 static int next_line_is_if(struct expression *expr)
  69 {
  70         struct expression *next;
  71
  72         if (!__next_stmt || __next_stmt->type != STMT_IF)
  73                 return 0;
  74
  75         next = strip_expr(__next_stmt->if_conditional);
  76         while (next->type == EXPR_PREOP && next->op == '!')
  77                 next = strip_expr(next->unop);
  78         if (expr_equiv(expr, next))
  79                 return 1;
  80         return 0;
  81 }
  82
  83 static int next_line_checks_IS_ERR(struct expression *call, struct expression *arg)
  84 {
  85         struct expression *next;
  86         struct expression *tmp;
  87
  88         tmp = expr_get_parent_expr(call);
  89         if (tmp && tmp->type == EXPR_ASSIGNMENT) {
  90                 if (next_line_checks_IS_ERR(NULL, tmp->left))
  91                         return 1;
  92         }
  93
  94         if (!__next_stmt || __next_stmt->type != STMT_IF)
  95                 return 0;
  96
  97         next = strip_expr(__next_stmt->if_conditional);
  98         while (next->type == EXPR_PREOP && next->op == '!')
  99                 next = strip_expr(next->unop);
 100         if (!next || next->type != EXPR_CALL)
 101                 return 0;
 102         if (next->fn->type != EXPR_SYMBOL || !next->fn->symbol ||
 103             !next->fn->symbol->ident ||
 104             (strcmp(next->fn->symbol->ident->name, "IS_ERR") != 0 &&
 105              strcmp(next->fn->symbol->ident->name, "IS_ERR_OR_NULL") != 0))
 106                 return 0;
 107         next = get_argument_from_call_expr(next->args, 0);
 108         return expr_equiv(next, arg);
 109 }
 110
 111 static int is_non_zero_int(struct range_list *rl)
 112 {
 113         struct data_range *tmp;
 114         int cnt = -1;
 115
 116         FOR_EACH_PTR(rl, tmp) {
 117                 cnt++;
 118
 119                 if (cnt == 0) {
 120                         if (tmp->min.value == INT_MIN &&
 121                             tmp->max.value == -1)
 122                                 continue;
 123                 } else if (cnt == 1) {
 124                         if (tmp->min.value == 1 &&
 125                             tmp->max.value == INT_MAX)
 126                                 return 1;
 127                 }
 128                 return 0;
 129         } END_FOR_EACH_PTR(tmp);
 130         return 0;
 131 }
 132
 133 static int is_valid_ptr(sval_t sval)
 134 {
 135         if (sval.value == INT_MIN || sval.value == INT_MAX)
 136                 return 0;
 137
 138         if (sval_cmp(valid_ptr_min_sval, sval) <= 0 &&
 139             sval_cmp(valid_ptr_max_sval, sval) >= 0) {
 140                 return 1;
 141         }
 142         return 0;
 143 }
 144
 145 static int has_distinct_zero(struct range_list *rl)
 146 {
 147         struct data_range *tmp;
 148
 149         FOR_EACH_PTR(rl, tmp) {
 150                 if (tmp->min.value == 0 || tmp->max.value == 0)
 151                         return 1;
 152         } END_FOR_EACH_PTR(tmp);
 153         return 0;
 154 }
 155
 156 static void match_err_ptr(const char *fn, struct expression *expr, void *data)
 157 {
 158         struct expression *arg_expr;
 159         struct sm_state *sm, *tmp;
 160
 161         if (is_impossible_path())
 162                 return;
 163
 164         arg_expr = get_argument_from_call_expr(expr->args, 0);
 165         sm = get_sm_state_expr(SMATCH_EXTRA, arg_expr);
 166         if (!sm)
 167                 return;
 168
 169         if (is_condition_expr(expr))
 170                 return;
 171
 172         if (next_line_checks_IS_ERR(expr, arg_expr))
 173                 return;
 174         if (strcmp(fn, "ERR_PTR") == 0 &&
 175             next_line_is_if(arg_expr))
 176                 return;
 177
 178         FOR_EACH_PTR(sm->possible, tmp) {
 179                 if (!estate_rl(tmp->state))
 180                         continue;
 181                 if (is_non_zero_int(estate_rl(tmp->state)))
 182                         continue;
 183                 if (has_distinct_zero(estate_rl(tmp->state))) {
 184                         sm_warning("passing zero to '%s'", fn);
 185                         return;
 186                 }
 187                 if (strcmp(fn, "PTR_ERR") != 0)
 188                         continue;
 189                 if (is_valid_ptr(estate_min(tmp->state)) &&
 190                     is_valid_ptr(estate_max(tmp->state))) {
 191                         sm_warning("passing a valid pointer to '%s'", fn);
 192                         return;
 193                 }
 194         } END_FOR_EACH_PTR(tmp);
 195 }
 196
 197 void check_zero_to_err_ptr(int id)
 198 {
 199         if (option_project != PROJ_KERNEL)
 200                 return;
 201
 202         my_id = id;
 203         add_function_hook("ERR_PTR", &match_err_ptr, NULL);
 204         add_function_hook("ERR_CAST", &match_err_ptr, NULL);
 205         add_function_hook("PTR_ERR", &match_err_ptr, NULL);
 206 }