check_kernel.c

   1 /*
   2  * sparse/check_kernel.c
   3  *
   4  * Copyright (C) 2010 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * This is kernel specific stuff for smatch_extra.
  12  */
  13
  14 #include "scope.h"
  15 #include "smatch.h"
  16 #include "smatch_extra.h"
  17
  18 static int implied_err_cast_return(struct expression *call, void *unused, struct range_list **rl)
  19 {
  20         struct expression *arg;
  21
  22         arg = get_argument_from_call_expr(call->args, 0);
  23         if (!get_implied_rl(arg, rl))
  24                 *rl = alloc_rl(ll_to_sval(-4095), ll_to_sval(-1));
  25         return 1;
  26 }
  27
  28 static int implied_copy_return(struct expression *call, void *unused, struct range_list **rl)
  29 {
  30         struct expression *arg;
  31         sval_t max;
  32
  33         arg = get_argument_from_call_expr(call->args, 2);
  34         get_absolute_max(arg, &max);
  35         *rl = alloc_rl(ll_to_sval(0), max);
  36         return 1;
  37 }
  38
  39 static void match_param_valid_ptr(const char *fn, struct expression *call_expr,
  40                         struct expression *assign_expr, void *_param)
  41 {
  42         int param = PTR_INT(_param);
  43         struct expression *arg;
  44         struct smatch_state *pre_state;
  45         struct smatch_state *end_state;
  46
  47         arg = get_argument_from_call_expr(call_expr->args, param);
  48         pre_state = get_state_expr(SMATCH_EXTRA, arg);
  49         end_state = estate_filter_range(pre_state, ll_to_sval(-4095), ll_to_sval(0));
  50         set_extra_expr_nomod(arg, end_state);
  51 }
  52
  53 static void match_param_err_or_null(const char *fn, struct expression *call_expr,
  54                         struct expression *assign_expr, void *_param)
  55 {
  56         int param = PTR_INT(_param);
  57         struct expression *arg;
  58         struct range_list *rl;
  59         struct smatch_state *pre_state;
  60         struct smatch_state *end_state;
  61
  62         arg = get_argument_from_call_expr(call_expr->args, param);
  63         pre_state = get_state_expr(SMATCH_EXTRA, arg);
  64         rl = alloc_rl(ll_to_sval(-4095), ll_to_sval(0));
  65         rl = rl_intersection(estate_rl(pre_state), rl);
  66         rl = cast_rl(estate_type(pre_state), rl);
  67         end_state = alloc_estate_rl(rl);
  68         set_extra_expr_nomod(arg, end_state);
  69 }
  70
  71 static void match_not_err(const char *fn, struct expression *call_expr,
  72                         struct expression *assign_expr, void *unused)
  73 {
  74         struct expression *arg;
  75         struct smatch_state *pre_state;
  76         struct smatch_state *new_state;
  77
  78         arg = get_argument_from_call_expr(call_expr->args, 0);
  79         pre_state = get_state_expr(SMATCH_EXTRA, arg);
  80         new_state = estate_filter_range(pre_state, sval_type_min(&long_ctype), ll_to_sval(-1));
  81         set_extra_expr_nomod(arg, new_state);
  82 }
  83
  84 static void match_err(const char *fn, struct expression *call_expr,
  85                         struct expression *assign_expr, void *unused)
  86 {
  87         struct expression *arg;
  88         struct smatch_state *pre_state;
  89         struct smatch_state *new_state;
  90
  91         arg = get_argument_from_call_expr(call_expr->args, 0);
  92         pre_state = get_state_expr(SMATCH_EXTRA, arg);
  93         new_state = estate_filter_range(pre_state, sval_type_min(&long_ctype), ll_to_sval(-4096));
  94         new_state = estate_filter_range(new_state, ll_to_sval(0), sval_type_max(&long_ctype));
  95         set_extra_expr_nomod(arg, new_state);
  96 }
  97
  98 static void match_container_of_macro(const char *fn, struct expression *expr, void *unused)
  99 {
 100         set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 101 }
 102
 103 static void match_container_of(struct expression *expr)
 104 {
 105         struct expression *right = expr->right;
 106         char *macro;
 107
 108         /*
 109          * The problem here is that sometimes the container_of() macro is itself
 110          * inside a macro and get_macro() only returns the name of the outside
 111          * macro.
 112          */
 113
 114         /*
 115          * This actually an expression statement assignment but smatch_flow
 116          * pre-mangles it for us so we only get the last chunk:
 117          * sk = (typeof(sk))((char *)__mptr - offsetof(...))
 118          */
 119
 120         macro = get_macro_name(right->pos);
 121         if (!macro)
 122                 return;
 123         if (right->type != EXPR_CAST)
 124                 return;
 125         right = strip_expr(right);
 126         if (right->type != EXPR_BINOP || right->op != '-' ||
 127             right->left->type != EXPR_CAST)
 128                 return;
 129         right = strip_expr(right->left);
 130         if (right->type != EXPR_SYMBOL)
 131                 return;
 132         if (!right->symbol->ident ||
 133             strcmp(right->symbol->ident->name, "__mptr") != 0)
 134                 return;
 135         set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 136 }
 137
 138 static int match_next_bit(struct expression *call, void *unused, struct range_list **rl)
 139 {
 140         struct expression *start_arg;
 141         struct expression *size_arg;
 142         struct symbol *type;
 143         sval_t min, max, tmp;
 144
 145         size_arg = get_argument_from_call_expr(call->args, 1);
 146         /* btw. there isn't a start_arg for find_first_bit() */
 147         start_arg = get_argument_from_call_expr(call->args, 2);
 148
 149         type = get_type(call);
 150         min = sval_type_val(type, 0);
 151         max = sval_type_val(type, sizeof(long long) * 8);
 152
 153         if (get_implied_max(size_arg, &tmp) && tmp.uvalue < max.value)
 154                 max = tmp;
 155         if (start_arg && get_implied_min(start_arg, &tmp) && !sval_is_negative(tmp))
 156                 min = tmp;
 157         if (sval_cmp(min, max) > 0)
 158                 max = min;
 159         min = sval_cast(type, min);
 160         max = sval_cast(type, max);
 161         *rl = alloc_rl(min, max);
 162         return 1;
 163 }
 164
 165 static void find_module_init_exit(struct symbol_list *sym_list)
 166 {
 167         struct symbol *sym;
 168         struct symbol *fn;
 169         struct statement *stmt;
 170         char *name;
 171         int init;
 172         int count;
 173
 174         /*
 175          * This is more complicated because Sparse ignores the "alias"
 176          * attribute.  I search backwards because module_init() is normally at
 177          * the end of the file.
 178          */
 179         count = 0;
 180         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 181                 if (sym->type != SYM_NODE)
 182                         continue;
 183                 if (!(sym->ctype.modifiers & MOD_STATIC))
 184                         continue;
 185                 fn = get_base_type(sym);
 186                 if (!fn)
 187                         continue;
 188                 if (fn->type != SYM_FN)
 189                         continue;
 190                 if (!sym->ident || !sym->ident->name)
 191                         continue;
 192                 if (!fn->inline_stmt)
 193                         continue;
 194                 if (strcmp(sym->ident->name, "__inittest") == 0)
 195                         init = 1;
 196                 else if (strcmp(sym->ident->name, "__exittest") == 0)
 197                         init = 0;
 198                 else
 199                         continue;
 200
 201                 count++;
 202
 203                 stmt = first_ptr_list((struct ptr_list *)fn->inline_stmt->stmts);
 204                 if (!stmt || stmt->type != STMT_RETURN)
 205                         continue;
 206                 name = expr_to_var(stmt->ret_value);
 207                 if (!name)
 208                         continue;
 209                 if (init)
 210                         sql_insert_function_ptr(name, "(struct module)->init");
 211                 else
 212                         sql_insert_function_ptr(name, "(struct module)->exit");
 213                 free_string(name);
 214                 if (count >= 2)
 215                         return;
 216         } END_FOR_EACH_PTR_REVERSE(sym);
 217 }
 218
 219 static void match_end_file(struct symbol_list *sym_list)
 220 {
 221         struct symbol *sym;
 222
 223         /* find the last static symbol in the file */
 224         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 225                 if (!(sym->ctype.modifiers & MOD_STATIC))
 226                         continue;
 227                 if (!sym->scope)
 228                         continue;
 229                 find_module_init_exit(sym->scope->symbols);
 230                 return;
 231         } END_FOR_EACH_PTR_REVERSE(sym);
 232 }
 233
 234 void check_kernel(int id)
 235 {
 236         if (option_project != PROJ_KERNEL)
 237                 return;
 238
 239         add_implied_return_hook("ERR_PTR", &implied_err_cast_return, NULL);
 240         add_implied_return_hook("ERR_CAST", &implied_err_cast_return, NULL);
 241         add_implied_return_hook("PTR_ERR", &implied_err_cast_return, NULL);
 242         return_implies_state("IS_ERR_OR_NULL", 0, 0, &match_param_valid_ptr, (void *)0);
 243         return_implies_state("IS_ERR_OR_NULL", 1, 1, &match_param_err_or_null, (void *)0);
 244         return_implies_state("IS_ERR", 0, 0, &match_not_err, NULL);
 245         return_implies_state("IS_ERR", 1, 1, &match_err, NULL);
 246         return_implies_state("tomoyo_memory_ok", 1, 1, &match_param_valid_ptr, (void *)0);
 247
 248         add_macro_assign_hook_extra("container_of", &match_container_of_macro, NULL);
 249         add_hook(match_container_of, ASSIGNMENT_HOOK);
 250
 251         add_implied_return_hook("copy_to_user", &implied_copy_return, NULL);
 252         add_implied_return_hook("__copy_to_user", &implied_copy_return, NULL);
 253         add_implied_return_hook("copy_from_user", &implied_copy_return, NULL);
 254         add_implied_return_hook("__copy_fom_user", &implied_copy_return, NULL);
 255         add_implied_return_hook("clear_user", &implied_copy_return, NULL);
 256
 257         add_implied_return_hook("find_next_bit", &match_next_bit, NULL);
 258         add_implied_return_hook("find_next_zero_bit", &match_next_bit, NULL);
 259         add_implied_return_hook("find_first_bit", &match_next_bit, NULL);
 260         add_implied_return_hook("find_first_zero_bit", &match_next_bit, NULL);
 261
 262         add_function_hook("__ftrace_bad_type", &__match_nullify_path_hook, NULL);
 263
 264         if (option_info)
 265                 add_hook(match_end_file, END_FILE_HOOK);
 266
 267 }