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 /*
 107  * GLib memory allocation functions.
 108  *
 109  * Note that we ignore the fact that g_malloc of 0 bytes returns NULL,
 110  * and g_realloc of 0 bytes frees the pointer.
 111  *
 112  * Modeling this would result in Coverity flagging a lot of memory
 113  * allocations as potentially returning NULL, and asking us to check
 114  * whether the result of the allocation is NULL or not.  However, the
 115  * resulting pointer should never be dereferenced anyway, and in fact
 116  * it is not in the vast majority of cases.
 117  *
 118  * If a dereference did happen, this would suppress a defect report
 119  * for an actual null pointer dereference.  But it's too unlikely to
 120  * be worth wading through the false positives, and with some luck
 121  * we'll get a buffer overflow reported anyway.
 122  */
 123
 124 /*
 125  * Allocation primitives, cannot return NULL
 126  * See also Coverity's library/generic/libc/all/all.c
 127  */
 128
 129 void *g_malloc_n(size_t nmemb, size_t size)
 130 {
 131     size_t sz;
 132     void *ptr;
 133
 134     __coverity_negative_sink__(nmemb);
 135     __coverity_negative_sink__(size);
 136     sz = nmemb * size;
 137     ptr = __coverity_alloc__(sz);
 138     __coverity_mark_as_uninitialized_buffer__(ptr);
 139     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 140     return ptr;
 141 }
 142
 143 void *g_malloc0_n(size_t nmemb, size_t size)
 144 {
 145     size_t sz;
 146     void *ptr;
 147
 148     __coverity_negative_sink__(nmemb);
 149     __coverity_negative_sink__(size);
 150     sz = nmemb * size;
 151     ptr = __coverity_alloc__(sz);
 152     __coverity_writeall0__(ptr);
 153     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 154     return ptr;
 155 }
 156
 157 void *g_realloc_n(void *ptr, size_t nmemb, size_t size)
 158 {
 159     size_t sz;
 160
 161     __coverity_negative_sink__(nmemb);
 162     __coverity_negative_sink__(size);
 163     sz = nmemb * size;
 164     __coverity_escape__(ptr);
 165     ptr = __coverity_alloc__(sz);
 166     /*
 167      * Memory beyond the old size isn't actually initialized.  Can't
 168      * model that.  See Coverity's realloc() model
 169      */
 170     __coverity_writeall__(ptr);
 171     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 172     return ptr;
 173 }
 174
 175 void g_free(void *ptr)
 176 {
 177     __coverity_free__(ptr);
 178     __coverity_mark_as_afm_freed__(ptr, "g_free");
 179 }
 180
 181 /*
 182  * Derive the g_try_FOO_n() from the g_FOO_n() by adding indeterminate
 183  * out of memory conditions
 184  */
 185
 186 void *g_try_malloc_n(size_t nmemb, size_t size)
 187 {
 188     int nomem;
 189
 190     if (nomem) {
 191         return NULL;
 192     }
 193     return g_malloc_n(nmemb, size);
 194 }
 195
 196 void *g_try_malloc0_n(size_t nmemb, size_t size)
 197 {
 198     int nomem;
 199
 200     if (nomem) {
 201         return NULL;
 202     }
 203     return g_malloc0_n(nmemb, size);
 204 }
 205
 206 void *g_try_realloc_n(void *ptr, size_t nmemb, size_t size)
 207 {
 208     int nomem;
 209
 210     if (nomem) {
 211         return NULL;
 212     }
 213     return g_realloc_n(ptr, nmemb, size);
 214 }
 215
 216 /* Trivially derive the g_FOO() from the g_FOO_n() */
 217
 218 void *g_malloc(size_t size)
 219 {
 220     return g_malloc_n(1, size);
 221 }
 222
 223 void *g_malloc0(size_t size)
 224 {
 225     return g_malloc0_n(1, size);
 226 }
 227
 228 void *g_realloc(void *ptr, size_t size)
 229 {
 230     return g_realloc_n(ptr, 1, size);
 231 }
 232
 233 void *g_try_malloc(size_t size)
 234 {
 235     return g_try_malloc_n(1, size);
 236 }
 237
 238 void *g_try_malloc0(size_t size)
 239 {
 240     return g_try_malloc0_n(1, size);
 241 }
 242
 243 void *g_try_realloc(void *ptr, size_t size)
 244 {
 245     return g_try_realloc_n(ptr, 1, size);
 246 }
 247
 248 /* Other memory allocation functions */
 249
 250 void *g_memdup(const void *ptr, unsigned size)
 251 {
 252     unsigned char *dup;
 253     unsigned i;
 254
 255     if (!ptr) {
 256         return NULL;
 257     }
 258
 259     dup = g_malloc(size);
 260     for (i = 0; i < size; i++)
 261         dup[i] = ((unsigned char *)ptr)[i];
 262     return dup;
 263 }
 264
 265 /*
 266  * GLib string allocation functions
 267  */
 268
 269 char *g_strdup(const char *s)
 270 {
 271     char *dup;
 272     size_t i;
 273
 274     if (!s) {
 275         return NULL;
 276     }
 277
 278     __coverity_string_null_sink__(s);
 279     __coverity_string_size_sink__(s);
 280     dup = __coverity_alloc_nosize__();
 281     __coverity_mark_as_afm_allocated__(dup, "g_free");
 282     for (i = 0; (dup[i] = s[i]); i++) ;
 283     return dup;
 284 }
 285
 286 char *g_strndup(const char *s, size_t n)
 287 {
 288     char *dup;
 289     size_t i;
 290
 291     __coverity_negative_sink__(n);
 292
 293     if (!s) {
 294         return NULL;
 295     }
 296
 297     dup = g_malloc(n + 1);
 298     for (i = 0; i < n && (dup[i] = s[i]); i++) ;
 299     dup[i] = 0;
 300     return dup;
 301 }
 302
 303 char *g_strdup_printf(const char *format, ...)
 304 {
 305     char ch, *s;
 306     size_t len;
 307
 308     __coverity_string_null_sink__(format);
 309     __coverity_string_size_sink__(format);
 310
 311     ch = *format;
 312
 313     s = __coverity_alloc_nosize__();
 314     __coverity_writeall__(s);
 315     __coverity_mark_as_afm_allocated__(s, "g_free");
 316     return s;
 317 }
 318
 319 char *g_strdup_vprintf(const char *format, va_list ap)
 320 {
 321     char ch, *s;
 322     size_t len;
 323
 324     __coverity_string_null_sink__(format);
 325     __coverity_string_size_sink__(format);
 326
 327     ch = *format;
 328     ch = *(char *)ap;
 329
 330     s = __coverity_alloc_nosize__();
 331     __coverity_writeall__(s);
 332     __coverity_mark_as_afm_allocated__(s, "g_free");
 333
 334     return len;
 335 }
 336
 337 char *g_strconcat(const char *s, ...)
 338 {
 339     char *s;
 340
 341     /*
 342      * Can't model: last argument must be null, the others
 343      * null-terminated strings
 344      */
 345
 346     s = __coverity_alloc_nosize__();
 347     __coverity_writeall__(s);
 348     __coverity_mark_as_afm_allocated__(s, "g_free");
 349     return s;
 350 }
 351
 352 /* Other glib functions */
 353
 354 typedef struct pollfd GPollFD;
 355
 356 int poll();
 357
 358 int g_poll (GPollFD *fds, unsigned nfds, int timeout)
 359 {
 360     return poll(fds, nfds, timeout);
 361 }
 362
 363 typedef struct _GIOChannel GIOChannel;
 364 GIOChannel *g_io_channel_unix_new(int fd)
 365 {
 366     GIOChannel *c = g_malloc0(sizeof(GIOChannel));
 367     __coverity_escape__(fd);
 368     return c;
 369 }
 370
 371 void g_assertion_message_expr(const char     *domain,
 372                               const char     *file,
 373                               int             line,
 374                               const char     *func,
 375                               const char     *expr)
 376 {
 377     __coverity_panic__();
 378 }