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 int is_comparison_call(struct expression *expr)
  25 {
  26         expr = expr_get_parent_expr(expr);
  27         if (!expr || expr->type != EXPR_COMPARE)
  28                 return 0;
  29         if (expr->op != SPECIAL_EQUAL && expr->op != SPECIAL_NOTEQUAL)
  30                 return 0;
  31         return 1;
  32 }
  33
  34 static int next_line_is_if(struct expression *expr)
  35 {
  36         struct expression *next;
  37
  38         if (!__next_stmt || __next_stmt->type != STMT_IF)
  39                 return 0;
  40
  41         next = strip_expr(__next_stmt->if_conditional);
  42         while (next->type == EXPR_PREOP && next->op == '!')
  43                 next = strip_expr(next->unop);
  44         if (expr_equiv(expr, next))
  45                 return 1;
  46         return 0;
  47 }
  48
  49 static int next_line_checks_IS_ERR(struct expression *call, struct expression *arg)
  50 {
  51         struct expression *next;
  52         struct expression *tmp;
  53
  54         tmp = expr_get_parent_expr(call);
  55         if (tmp && tmp->type == EXPR_ASSIGNMENT) {
  56                 if (next_line_checks_IS_ERR(NULL, tmp->left))
  57                         return 1;
  58         }
  59
  60         if (!__next_stmt || __next_stmt->type != STMT_IF)
  61                 return 0;
  62
  63         next = strip_expr(__next_stmt->if_conditional);
  64         while (next->type == EXPR_PREOP && next->op == '!')
  65                 next = strip_expr(next->unop);
  66         if (!next || next->type != EXPR_CALL)
  67                 return 0;
  68         if (next->fn->type != EXPR_SYMBOL || !next->fn->symbol ||
  69             !next->fn->symbol->ident ||
  70             (strcmp(next->fn->symbol->ident->name, "IS_ERR") != 0 &&
  71              strcmp(next->fn->symbol->ident->name, "IS_ERR_OR_NULL") != 0))
  72                 return 0;
  73         next = get_argument_from_call_expr(next->args, 0);
  74         return expr_equiv(next, arg);
  75 }
  76
  77 static int is_non_zero_int(struct range_list *rl)
  78 {
  79         struct data_range *tmp;
  80         int cnt = -1;
  81
  82         FOR_EACH_PTR(rl, tmp) {
  83                 cnt++;
  84
  85                 if (cnt == 0) {
  86                         if (tmp->min.value == INT_MIN &&
  87                             tmp->max.value == -1)
  88                                 continue;
  89                 } else if (cnt == 1) {
  90                         if (tmp->min.value == 1 &&
  91                             tmp->max.value == INT_MAX)
  92                                 return 1;
  93                 }
  94                 return 0;
  95         } END_FOR_EACH_PTR(tmp);
  96         return 0;
  97 }
  98
  99 static int is_valid_ptr(sval_t sval)
 100 {
 101         if (sval.value == INT_MIN || sval.value == INT_MAX)
 102                 return 0;
 103
 104         if (sval_cmp(valid_ptr_min_sval, sval) <= 0 &&
 105             sval_cmp(valid_ptr_max_sval, sval) >= 0) {
 106                 return 1;
 107         }
 108         return 0;
 109 }
 110
 111 static int has_distinct_zero(struct range_list *rl)
 112 {
 113         struct data_range *tmp;
 114
 115         FOR_EACH_PTR(rl, tmp) {
 116                 if (tmp->min.value == 0 || tmp->max.value == 0)
 117                         return 1;
 118         } END_FOR_EACH_PTR(tmp);
 119         return 0;
 120 }
 121
 122 static void match_err_ptr(const char *fn, struct expression *expr, void *data)
 123 {
 124         struct expression *arg_expr;
 125         struct sm_state *sm, *tmp;
 126
 127         if (is_impossible_path())
 128                 return;
 129
 130         arg_expr = get_argument_from_call_expr(expr->args, 0);
 131         sm = get_sm_state_expr(SMATCH_EXTRA, arg_expr);
 132         if (!sm)
 133                 return;
 134
 135         if (is_comparison_call(expr))
 136                 return;
 137
 138         if (next_line_checks_IS_ERR(expr, arg_expr))
 139                 return;
 140         if (strcmp(fn, "ERR_PTR") == 0 &&
 141             next_line_is_if(arg_expr))
 142                 return;
 143
 144         FOR_EACH_PTR(sm->possible, tmp) {
 145                 if (!estate_rl(tmp->state))
 146                         continue;
 147                 if (is_non_zero_int(estate_rl(tmp->state)))
 148                         continue;
 149                 if (has_distinct_zero(estate_rl(tmp->state))) {
 150                         sm_warning("passing zero to '%s'", fn);
 151                         return;
 152                 }
 153                 if (strcmp(fn, "PTR_ERR") != 0)
 154                         continue;
 155                 if (is_valid_ptr(estate_min(tmp->state)) &&
 156                     is_valid_ptr(estate_max(tmp->state))) {
 157                         sm_warning("passing a valid pointer to '%s'", fn);
 158                         return;
 159                 }
 160         } END_FOR_EACH_PTR(tmp);
 161 }
 162
 163 void check_zero_to_err_ptr(int id)
 164 {
 165         if (option_project != PROJ_KERNEL)
 166                 return;
 167
 168         my_id = id;
 169         add_function_hook("ERR_PTR", &match_err_ptr, NULL);
 170         add_function_hook("ERR_CAST", &match_err_ptr, NULL);
 171         add_function_hook("PTR_ERR", &match_err_ptr, NULL);
 172 }