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 int next_line_is_if(struct expression *expr)
  50 {
  51         struct expression *next;
  52
  53         if (!__next_stmt || __next_stmt->type != STMT_IF)
  54                 return 0;
  55
  56         next = strip_expr(__next_stmt->if_conditional);
  57         while (next->type == EXPR_PREOP && next->op == '!')
  58                 next = strip_expr(next->unop);
  59         if (expr_equiv(expr, next))
  60                 return 1;
  61         return 0;
  62 }
  63
  64 static int next_line_checks_IS_ERR(struct expression *call, struct expression *arg)
  65 {
  66         struct expression *next;
  67         struct expression *tmp;
  68
  69         tmp = expr_get_parent_expr(call);
  70         if (tmp && tmp->type == EXPR_ASSIGNMENT) {
  71                 if (next_line_checks_IS_ERR(NULL, tmp->left))
  72                         return 1;
  73         }
  74
  75         if (!__next_stmt || __next_stmt->type != STMT_IF)
  76                 return 0;
  77
  78         next = strip_expr(__next_stmt->if_conditional);
  79         while (next->type == EXPR_PREOP && next->op == '!')
  80                 next = strip_expr(next->unop);
  81         if (!next || next->type != EXPR_CALL)
  82                 return 0;
  83         if (next->fn->type != EXPR_SYMBOL || !next->fn->symbol ||
  84             !next->fn->symbol->ident ||
  85             (strcmp(next->fn->symbol->ident->name, "IS_ERR") != 0 &&
  86              strcmp(next->fn->symbol->ident->name, "IS_ERR_OR_NULL") != 0))
  87                 return 0;
  88         next = get_argument_from_call_expr(next->args, 0);
  89         return expr_equiv(next, arg);
  90 }
  91
  92 static int is_non_zero_int(struct range_list *rl)
  93 {
  94         struct data_range *tmp;
  95         int cnt = -1;
  96
  97         FOR_EACH_PTR(rl, tmp) {
  98                 cnt++;
  99
 100                 if (cnt == 0) {
 101                         if (tmp->min.value == INT_MIN &&
 102                             tmp->max.value == -1)
 103                                 continue;
 104                 } else if (cnt == 1) {
 105                         if (tmp->min.value == 1 &&
 106                             tmp->max.value == INT_MAX)
 107                                 return 1;
 108                 }
 109                 return 0;
 110         } END_FOR_EACH_PTR(tmp);
 111         return 0;
 112 }
 113
 114 static int is_valid_ptr(sval_t sval)
 115 {
 116         if (sval.value == INT_MIN || sval.value == INT_MAX)
 117                 return 0;
 118
 119         if (sval_cmp(valid_ptr_min_sval, sval) <= 0 &&
 120             sval_cmp(valid_ptr_max_sval, sval) >= 0) {
 121                 return 1;
 122         }
 123         return 0;
 124 }
 125
 126 static int has_distinct_zero(struct range_list *rl)
 127 {
 128         struct data_range *tmp;
 129
 130         FOR_EACH_PTR(rl, tmp) {
 131                 if (tmp->min.value == 0 || tmp->max.value == 0)
 132                         return 1;
 133         } END_FOR_EACH_PTR(tmp);
 134         return 0;
 135 }
 136
 137 static void match_err_ptr(const char *fn, struct expression *expr, void *data)
 138 {
 139         struct expression *arg_expr;
 140         struct sm_state *sm, *tmp;
 141
 142         if (is_impossible_path())
 143                 return;
 144
 145         arg_expr = get_argument_from_call_expr(expr->args, 0);
 146         sm = get_sm_state_expr(SMATCH_EXTRA, arg_expr);
 147         if (!sm)
 148                 return;
 149
 150         if (is_comparison_call(expr))
 151                 return;
 152         if (is_select_assign(expr))
 153                 return;
 154
 155         if (next_line_checks_IS_ERR(expr, arg_expr))
 156                 return;
 157         if (strcmp(fn, "ERR_PTR") == 0 &&
 158             next_line_is_if(arg_expr))
 159                 return;
 160
 161         FOR_EACH_PTR(sm->possible, tmp) {
 162                 if (!estate_rl(tmp->state))
 163                         continue;
 164                 if (is_non_zero_int(estate_rl(tmp->state)))
 165                         continue;
 166                 if (has_distinct_zero(estate_rl(tmp->state))) {
 167                         sm_warning("passing zero to '%s'", fn);
 168                         return;
 169                 }
 170                 if (strcmp(fn, "PTR_ERR") != 0)
 171                         continue;
 172                 if (is_valid_ptr(estate_min(tmp->state)) &&
 173                     is_valid_ptr(estate_max(tmp->state))) {
 174                         sm_warning("passing a valid pointer to '%s'", fn);
 175                         return;
 176                 }
 177         } END_FOR_EACH_PTR(tmp);
 178 }
 179
 180 void check_zero_to_err_ptr(int id)
 181 {
 182         if (option_project != PROJ_KERNEL)
 183                 return;
 184
 185         my_id = id;
 186         add_function_hook("ERR_PTR", &match_err_ptr, NULL);
 187         add_function_hook("ERR_CAST", &match_err_ptr, NULL);
 188         add_function_hook("PTR_ERR", &match_err_ptr, NULL);
 189 }