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 = 0;
 110      if (replay_file) {
 111          uint8_t c;
 112          byte = c;
 113      }
 114      return byte;
 115 }
 116
 117
 118 /*
 119  * GLib memory allocation functions.
 120  *
 121  * Note that we ignore the fact that g_malloc of 0 bytes returns NULL,
 122  * and g_realloc of 0 bytes frees the pointer.
 123  *
 124  * Modeling this would result in Coverity flagging a lot of memory
 125  * allocations as potentially returning NULL, and asking us to check
 126  * whether the result of the allocation is NULL or not.  However, the
 127  * resulting pointer should never be dereferenced anyway, and in fact
 128  * it is not in the vast majority of cases.
 129  *
 130  * If a dereference did happen, this would suppress a defect report
 131  * for an actual null pointer dereference.  But it's too unlikely to
 132  * be worth wading through the false positives, and with some luck
 133  * we'll get a buffer overflow reported anyway.
 134  */
 135
 136 /*
 137  * Allocation primitives, cannot return NULL
 138  * See also Coverity's library/generic/libc/all/all.c
 139  */
 140
 141 void *g_malloc_n(size_t nmemb, size_t size)
 142 {
 143     size_t sz;
 144     void *ptr;
 145
 146     __coverity_negative_sink__(nmemb);
 147     __coverity_negative_sink__(size);
 148     sz = nmemb * size;
 149     ptr = __coverity_alloc__(sz);
 150     __coverity_mark_as_uninitialized_buffer__(ptr);
 151     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 152     return ptr;
 153 }
 154
 155 void *g_malloc0_n(size_t nmemb, size_t size)
 156 {
 157     size_t sz;
 158     void *ptr;
 159
 160     __coverity_negative_sink__(nmemb);
 161     __coverity_negative_sink__(size);
 162     sz = nmemb * size;
 163     ptr = __coverity_alloc__(sz);
 164     __coverity_writeall0__(ptr);
 165     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 166     return ptr;
 167 }
 168
 169 void *g_realloc_n(void *ptr, size_t nmemb, size_t size)
 170 {
 171     size_t sz;
 172
 173     __coverity_negative_sink__(nmemb);
 174     __coverity_negative_sink__(size);
 175     sz = nmemb * size;
 176     __coverity_escape__(ptr);
 177     ptr = __coverity_alloc__(sz);
 178     /*
 179      * Memory beyond the old size isn't actually initialized.  Can't
 180      * model that.  See Coverity's realloc() model
 181      */
 182     __coverity_writeall__(ptr);
 183     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 184     return ptr;
 185 }
 186
 187 void g_free(void *ptr)
 188 {
 189     __coverity_free__(ptr);
 190     __coverity_mark_as_afm_freed__(ptr, "g_free");
 191 }
 192
 193 /*
 194  * Derive the g_try_FOO_n() from the g_FOO_n() by adding indeterminate
 195  * out of memory conditions
 196  */
 197
 198 void *g_try_malloc_n(size_t nmemb, size_t size)
 199 {
 200     int nomem;
 201
 202     if (nomem) {
 203         return NULL;
 204     }
 205     return g_malloc_n(nmemb, size);
 206 }
 207
 208 void *g_try_malloc0_n(size_t nmemb, size_t size)
 209 {
 210     int nomem;
 211
 212     if (nomem) {
 213         return NULL;
 214     }
 215     return g_malloc0_n(nmemb, size);
 216 }
 217
 218 void *g_try_realloc_n(void *ptr, size_t nmemb, size_t size)
 219 {
 220     int nomem;
 221
 222     if (nomem) {
 223         return NULL;
 224     }
 225     return g_realloc_n(ptr, nmemb, size);
 226 }
 227
 228 /* Trivially derive the g_FOO() from the g_FOO_n() */
 229
 230 void *g_malloc(size_t size)
 231 {
 232     return g_malloc_n(1, size);
 233 }
 234
 235 void *g_malloc0(size_t size)
 236 {
 237     return g_malloc0_n(1, size);
 238 }
 239
 240 void *g_realloc(void *ptr, size_t size)
 241 {
 242     return g_realloc_n(ptr, 1, size);
 243 }
 244
 245 void *g_try_malloc(size_t size)
 246 {
 247     return g_try_malloc_n(1, size);
 248 }
 249
 250 void *g_try_malloc0(size_t size)
 251 {
 252     return g_try_malloc0_n(1, size);
 253 }
 254
 255 void *g_try_realloc(void *ptr, size_t size)
 256 {
 257     return g_try_realloc_n(ptr, 1, size);
 258 }
 259
 260 /* Other memory allocation functions */
 261
 262 void *g_memdup(const void *ptr, unsigned size)
 263 {
 264     unsigned char *dup;
 265     unsigned i;
 266
 267     if (!ptr) {
 268         return NULL;
 269     }
 270
 271     dup = g_malloc(size);
 272     for (i = 0; i < size; i++)
 273         dup[i] = ((unsigned char *)ptr)[i];
 274     return dup;
 275 }
 276
 277 /*
 278  * GLib string allocation functions
 279  */
 280
 281 char *g_strdup(const char *s)
 282 {
 283     char *dup;
 284     size_t i;
 285
 286     if (!s) {
 287         return NULL;
 288     }
 289
 290     __coverity_string_null_sink__(s);
 291     __coverity_string_size_sink__(s);
 292     dup = __coverity_alloc_nosize__();
 293     __coverity_mark_as_afm_allocated__(dup, "g_free");
 294     for (i = 0; (dup[i] = s[i]); i++) ;
 295     return dup;
 296 }
 297
 298 char *g_strndup(const char *s, size_t n)
 299 {
 300     char *dup;
 301     size_t i;
 302
 303     __coverity_negative_sink__(n);
 304
 305     if (!s) {
 306         return NULL;
 307     }
 308
 309     dup = g_malloc(n + 1);
 310     for (i = 0; i < n && (dup[i] = s[i]); i++) ;
 311     dup[i] = 0;
 312     return dup;
 313 }
 314
 315 char *g_strdup_printf(const char *format, ...)
 316 {
 317     char ch, *s;
 318     size_t len;
 319
 320     __coverity_string_null_sink__(format);
 321     __coverity_string_size_sink__(format);
 322
 323     ch = *format;
 324
 325     s = __coverity_alloc_nosize__();
 326     __coverity_writeall__(s);
 327     __coverity_mark_as_afm_allocated__(s, "g_free");
 328     return s;
 329 }
 330
 331 char *g_strdup_vprintf(const char *format, va_list ap)
 332 {
 333     char ch, *s;
 334     size_t len;
 335
 336     __coverity_string_null_sink__(format);
 337     __coverity_string_size_sink__(format);
 338
 339     ch = *format;
 340     ch = *(char *)ap;
 341
 342     s = __coverity_alloc_nosize__();
 343     __coverity_writeall__(s);
 344     __coverity_mark_as_afm_allocated__(s, "g_free");
 345
 346     return len;
 347 }
 348
 349 char *g_strconcat(const char *s, ...)
 350 {
 351     char *s;
 352
 353     /*
 354      * Can't model: last argument must be null, the others
 355      * null-terminated strings
 356      */
 357
 358     s = __coverity_alloc_nosize__();
 359     __coverity_writeall__(s);
 360     __coverity_mark_as_afm_allocated__(s, "g_free");
 361     return s;
 362 }
 363
 364 /* Other glib functions */
 365
 366 typedef struct pollfd GPollFD;
 367
 368 int poll();
 369
 370 int g_poll (GPollFD *fds, unsigned nfds, int timeout)
 371 {
 372     return poll(fds, nfds, timeout);
 373 }
 374
 375 typedef struct _GIOChannel GIOChannel;
 376 GIOChannel *g_io_channel_unix_new(int fd)
 377 {
 378     GIOChannel *c = g_malloc0(sizeof(GIOChannel));
 379     __coverity_escape__(fd);
 380     return c;
 381 }
 382
 383 void g_assertion_message_expr(const char     *domain,
 384                               const char     *file,
 385                               int             line,
 386                               const char     *func,
 387                               const char     *expr)
 388 {
 389     __coverity_panic__();
 390 }