scripts/coverity-model.c

   1 /* Coverity Scan model
   2  *
   3  * Copyright (C) 2014 Red Hat, Inc.
   4  *
   5  * Authors:
   6  *  Markus Armbruster <armbru@redhat.com>
   7  *  Paolo Bonzini <pbonzini@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or, at your
  10  * option, any later version.  See the COPYING file in the top-level directory.
  11  */
  12
  13
  14 /*
  15  * This is the source code for our Coverity user model file.  The
  16  * purpose of user models is to increase scanning accuracy by explaining
  17  * code Coverity can't see (out of tree libraries) or doesn't
  18  * sufficiently understand.  Better accuracy means both fewer false
  19  * positives and more true defects.  Memory leaks in particular.
  20  *
  21  * - A model file can't import any header files.  Some built-in primitives are
  22  *   available but not wchar_t, NULL etc.
  23  * - Modeling doesn't need full structs and typedefs. Rudimentary structs
  24  *   and similar types are sufficient.
  25  * - An uninitialized local variable signifies that the variable could be
  26  *   any value.
  27  *
  28  * The model file must be uploaded by an admin in the analysis settings of
  29  * http://scan.coverity.com/projects/378
  30  */
  31
  32 #define NULL ((void *)0)
  33
  34 typedef unsigned char uint8_t;
  35 typedef char int8_t;
  36 typedef unsigned int uint32_t;
  37 typedef int int32_t;
  38 typedef long ssize_t;
  39 typedef unsigned long long uint64_t;
  40 typedef long long int64_t;
  41 typedef _Bool bool;
  42
  43 typedef struct va_list_str *va_list;
  44
  45 /* exec.c */
  46
  47 typedef struct AddressSpace AddressSpace;
  48 typedef uint64_t hwaddr;
  49 typedef uint32_t MemTxResult;
  50 typedef uint64_t MemTxAttrs;
  51
  52 static void __bufwrite(uint8_t *buf, ssize_t len)
  53 {
  54     int first, last;
  55     __coverity_negative_sink__(len);
  56     if (len == 0) return;
  57     buf[0] = first;
  58     buf[len-1] = last;
  59     __coverity_writeall__(buf);
  60 }
  61
  62 static void __bufread(uint8_t *buf, ssize_t len)
  63 {
  64     __coverity_negative_sink__(len);
  65     if (len == 0) return;
  66     int first = buf[0];
  67     int last = buf[len-1];
  68 }
  69
  70 MemTxResult address_space_read(AddressSpace *as, hwaddr addr,
  71                                MemTxAttrs attrs,
  72                                uint8_t *buf, int len)
  73 {
  74     MemTxResult result;
  75     // TODO: investigate impact of treating reads as producing
  76     // tainted data, with __coverity_tainted_data_argument__(buf).
  77     __bufwrite(buf, len);
  78     return result;
  79 }
  80
  81 MemTxResult address_space_write(AddressSpace *as, hwaddr addr,
  82                                 MemTxAttrs attrs,
  83                                 const uint8_t *buf, int len)
  84 {
  85     MemTxResult result;
  86     __bufread(buf, len);
  87     return result;
  88 }
  89
  90
  91 /* Tainting */
  92
  93 typedef struct {} name2keysym_t;
  94 static int get_keysym(const name2keysym_t *table,
  95                       const char *name)
  96 {
  97     int result;
  98     if (result > 0) {
  99         __coverity_tainted_string_sanitize_content__(name);
 100         return result;
 101     } else {
 102         return 0;
 103     }
 104 }
 105
 106 /* Replay data is considered trusted.  */
 107 uint8_t replay_get_byte(void)
 108 {
 109     uint8_t byte;
 110     return byte;
 111 }
 112
 113
 114 /*
 115  * GLib memory allocation functions.
 116  *
 117  * Note that we ignore the fact that g_malloc of 0 bytes returns NULL,
 118  * and g_realloc of 0 bytes frees the pointer.
 119  *
 120  * Modeling this would result in Coverity flagging a lot of memory
 121  * allocations as potentially returning NULL, and asking us to check
 122  * whether the result of the allocation is NULL or not.  However, the
 123  * resulting pointer should never be dereferenced anyway, and in fact
 124  * it is not in the vast majority of cases.
 125  *
 126  * If a dereference did happen, this would suppress a defect report
 127  * for an actual null pointer dereference.  But it's too unlikely to
 128  * be worth wading through the false positives, and with some luck
 129  * we'll get a buffer overflow reported anyway.
 130  */
 131
 132 /*
 133  * Allocation primitives, cannot return NULL
 134  * See also Coverity's library/generic/libc/all/all.c
 135  */
 136
 137 void *g_malloc_n(size_t nmemb, size_t size)
 138 {
 139     size_t sz;
 140     void *ptr;
 141
 142     __coverity_negative_sink__(nmemb);
 143     __coverity_negative_sink__(size);
 144     sz = nmemb * size;
 145     ptr = __coverity_alloc__(sz);
 146     __coverity_mark_as_uninitialized_buffer__(ptr);
 147     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 148     return ptr;
 149 }
 150
 151 void *g_malloc0_n(size_t nmemb, size_t size)
 152 {
 153     size_t sz;
 154     void *ptr;
 155
 156     __coverity_negative_sink__(nmemb);
 157     __coverity_negative_sink__(size);
 158     sz = nmemb * size;
 159     ptr = __coverity_alloc__(sz);
 160     __coverity_writeall0__(ptr);
 161     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 162     return ptr;
 163 }
 164
 165 void *g_realloc_n(void *ptr, size_t nmemb, size_t size)
 166 {
 167     size_t sz;
 168
 169     __coverity_negative_sink__(nmemb);
 170     __coverity_negative_sink__(size);
 171     sz = nmemb * size;
 172     __coverity_escape__(ptr);
 173     ptr = __coverity_alloc__(sz);
 174     /*
 175      * Memory beyond the old size isn't actually initialized.  Can't
 176      * model that.  See Coverity's realloc() model
 177      */
 178     __coverity_writeall__(ptr);
 179     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 180     return ptr;
 181 }
 182
 183 void g_free(void *ptr)
 184 {
 185     __coverity_free__(ptr);
 186     __coverity_mark_as_afm_freed__(ptr, "g_free");
 187 }
 188
 189 /*
 190  * Derive the g_try_FOO_n() from the g_FOO_n() by adding indeterminate
 191  * out of memory conditions
 192  */
 193
 194 void *g_try_malloc_n(size_t nmemb, size_t size)
 195 {
 196     int nomem;
 197
 198     if (nomem) {
 199         return NULL;
 200     }
 201     return g_malloc_n(nmemb, size);
 202 }
 203
 204 void *g_try_malloc0_n(size_t nmemb, size_t size)
 205 {
 206     int nomem;
 207
 208     if (nomem) {
 209         return NULL;
 210     }
 211     return g_malloc0_n(nmemb, size);
 212 }
 213
 214 void *g_try_realloc_n(void *ptr, size_t nmemb, size_t size)
 215 {
 216     int nomem;
 217
 218     if (nomem) {
 219         return NULL;
 220     }
 221     return g_realloc_n(ptr, nmemb, size);
 222 }
 223
 224 /* Trivially derive the g_FOO() from the g_FOO_n() */
 225
 226 void *g_malloc(size_t size)
 227 {
 228     return g_malloc_n(1, size);
 229 }
 230
 231 void *g_malloc0(size_t size)
 232 {
 233     return g_malloc0_n(1, size);
 234 }
 235
 236 void *g_realloc(void *ptr, size_t size)
 237 {
 238     return g_realloc_n(ptr, 1, size);
 239 }
 240
 241 void *g_try_malloc(size_t size)
 242 {
 243     return g_try_malloc_n(1, size);
 244 }
 245
 246 void *g_try_malloc0(size_t size)
 247 {
 248     return g_try_malloc0_n(1, size);
 249 }
 250
 251 void *g_try_realloc(void *ptr, size_t size)
 252 {
 253     return g_try_realloc_n(ptr, 1, size);
 254 }
 255
 256 /* Other memory allocation functions */
 257
 258 void *g_memdup(const void *ptr, unsigned size)
 259 {
 260     unsigned char *dup;
 261     unsigned i;
 262
 263     if (!ptr) {
 264         return NULL;
 265     }
 266
 267     dup = g_malloc(size);
 268     for (i = 0; i < size; i++)
 269         dup[i] = ((unsigned char *)ptr)[i];
 270     return dup;
 271 }
 272
 273 /*
 274  * GLib string allocation functions
 275  */
 276
 277 char *g_strdup(const char *s)
 278 {
 279     char *dup;
 280     size_t i;
 281
 282     if (!s) {
 283         return NULL;
 284     }
 285
 286     __coverity_string_null_sink__(s);
 287     __coverity_string_size_sink__(s);
 288     dup = __coverity_alloc_nosize__();
 289     __coverity_mark_as_afm_allocated__(dup, "g_free");
 290     for (i = 0; (dup[i] = s[i]); i++) ;
 291     return dup;
 292 }
 293
 294 char *g_strndup(const char *s, size_t n)
 295 {
 296     char *dup;
 297     size_t i;
 298
 299     __coverity_negative_sink__(n);
 300
 301     if (!s) {
 302         return NULL;
 303     }
 304
 305     dup = g_malloc(n + 1);
 306     for (i = 0; i < n && (dup[i] = s[i]); i++) ;
 307     dup[i] = 0;
 308     return dup;
 309 }
 310
 311 char *g_strdup_printf(const char *format, ...)
 312 {
 313     char ch, *s;
 314     size_t len;
 315
 316     __coverity_string_null_sink__(format);
 317     __coverity_string_size_sink__(format);
 318
 319     ch = *format;
 320
 321     s = __coverity_alloc_nosize__();
 322     __coverity_writeall__(s);
 323     __coverity_mark_as_afm_allocated__(s, "g_free");
 324     return s;
 325 }
 326
 327 char *g_strdup_vprintf(const char *format, va_list ap)
 328 {
 329     char ch, *s;
 330     size_t len;
 331
 332     __coverity_string_null_sink__(format);
 333     __coverity_string_size_sink__(format);
 334
 335     ch = *format;
 336     ch = *(char *)ap;
 337
 338     s = __coverity_alloc_nosize__();
 339     __coverity_writeall__(s);
 340     __coverity_mark_as_afm_allocated__(s, "g_free");
 341
 342     return len;
 343 }
 344
 345 char *g_strconcat(const char *s, ...)
 346 {
 347     char *s;
 348
 349     /*
 350      * Can't model: last argument must be null, the others
 351      * null-terminated strings
 352      */
 353
 354     s = __coverity_alloc_nosize__();
 355     __coverity_writeall__(s);
 356     __coverity_mark_as_afm_allocated__(s, "g_free");
 357     return s;
 358 }
 359
 360 /* Other glib functions */
 361
 362 typedef struct pollfd GPollFD;
 363
 364 int poll();
 365
 366 int g_poll (GPollFD *fds, unsigned nfds, int timeout)
 367 {
 368     return poll(fds, nfds, timeout);
 369 }
 370
 371 typedef struct _GIOChannel GIOChannel;
 372 GIOChannel *g_io_channel_unix_new(int fd)
 373 {
 374     GIOChannel *c = g_malloc0(sizeof(GIOChannel));
 375     __coverity_escape__(fd);
 376     return c;
 377 }
 378
 379 void g_assertion_message_expr(const char     *domain,
 380                               const char     *file,
 381                               int             line,
 382                               const char     *func,
 383                               const char     *expr)
 384 {
 385     __coverity_panic__();
 386 }