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 __write(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 __read(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_rw(AddressSpace *as, hwaddr addr, MemTxAttrs attrs,
  71                              uint8_t *buf, int len, bool is_write)
  72 {
  73     MemTxResult result;
  74
  75     // TODO: investigate impact of treating reads as producing
  76     // tainted data, with __coverity_tainted_data_argument__(buf).
  77     if (is_write) __write(buf, len); else __read(buf, len);
  78
  79     return result;
  80 }
  81
  82 /* Tainting */
  83
  84 typedef struct {} name2keysym_t;
  85 static int get_keysym(const name2keysym_t *table,
  86                       const char *name)
  87 {
  88     int result;
  89     if (result > 0) {
  90         __coverity_tainted_string_sanitize_content__(name);
  91         return result;
  92     } else {
  93         return 0;
  94     }
  95 }
  96
  97 /*
  98  * GLib memory allocation functions.
  99  *
 100  * Note that we ignore the fact that g_malloc of 0 bytes returns NULL,
 101  * and g_realloc of 0 bytes frees the pointer.
 102  *
 103  * Modeling this would result in Coverity flagging a lot of memory
 104  * allocations as potentially returning NULL, and asking us to check
 105  * whether the result of the allocation is NULL or not.  However, the
 106  * resulting pointer should never be dereferenced anyway, and in fact
 107  * it is not in the vast majority of cases.
 108  *
 109  * If a dereference did happen, this would suppress a defect report
 110  * for an actual null pointer dereference.  But it's too unlikely to
 111  * be worth wading through the false positives, and with some luck
 112  * we'll get a buffer overflow reported anyway.
 113  */
 114
 115 /*
 116  * Allocation primitives, cannot return NULL
 117  * See also Coverity's library/generic/libc/all/all.c
 118  */
 119
 120 void *g_malloc_n(size_t nmemb, size_t size)
 121 {
 122     size_t sz;
 123     void *ptr;
 124
 125     __coverity_negative_sink__(nmemb);
 126     __coverity_negative_sink__(size);
 127     sz = nmemb * size;
 128     ptr = __coverity_alloc__(sz);
 129     __coverity_mark_as_uninitialized_buffer__(ptr);
 130     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 131     return ptr;
 132 }
 133
 134 void *g_malloc0_n(size_t nmemb, size_t size)
 135 {
 136     size_t sz;
 137     void *ptr;
 138
 139     __coverity_negative_sink__(nmemb);
 140     __coverity_negative_sink__(size);
 141     sz = nmemb * size;
 142     ptr = __coverity_alloc__(sz);
 143     __coverity_writeall0__(ptr);
 144     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 145     return ptr;
 146 }
 147
 148 void *g_realloc_n(void *ptr, size_t nmemb, size_t size)
 149 {
 150     size_t sz;
 151
 152     __coverity_negative_sink__(nmemb);
 153     __coverity_negative_sink__(size);
 154     sz = nmemb * size;
 155     __coverity_escape__(ptr);
 156     ptr = __coverity_alloc__(sz);
 157     /*
 158      * Memory beyond the old size isn't actually initialized.  Can't
 159      * model that.  See Coverity's realloc() model
 160      */
 161     __coverity_writeall__(ptr);
 162     __coverity_mark_as_afm_allocated__(ptr, "g_free");
 163     return ptr;
 164 }
 165
 166 void g_free(void *ptr)
 167 {
 168     __coverity_free__(ptr);
 169     __coverity_mark_as_afm_freed__(ptr, "g_free");
 170 }
 171
 172 /*
 173  * Derive the g_try_FOO_n() from the g_FOO_n() by adding indeterminate
 174  * out of memory conditions
 175  */
 176
 177 void *g_try_malloc_n(size_t nmemb, size_t size)
 178 {
 179     int nomem;
 180
 181     if (nomem) {
 182         return NULL;
 183     }
 184     return g_malloc_n(nmemb, size);
 185 }
 186
 187 void *g_try_malloc0_n(size_t nmemb, size_t size)
 188 {
 189     int nomem;
 190
 191     if (nomem) {
 192         return NULL;
 193     }
 194     return g_malloc0_n(nmemb, size);
 195 }
 196
 197 void *g_try_realloc_n(void *ptr, size_t nmemb, size_t size)
 198 {
 199     int nomem;
 200
 201     if (nomem) {
 202         return NULL;
 203     }
 204     return g_realloc_n(ptr, nmemb, size);
 205 }
 206
 207 /* Trivially derive the g_FOO() from the g_FOO_n() */
 208
 209 void *g_malloc(size_t size)
 210 {
 211     return g_malloc_n(1, size);
 212 }
 213
 214 void *g_malloc0(size_t size)
 215 {
 216     return g_malloc0_n(1, size);
 217 }
 218
 219 void *g_realloc(void *ptr, size_t size)
 220 {
 221     return g_realloc_n(ptr, 1, size);
 222 }
 223
 224 void *g_try_malloc(size_t size)
 225 {
 226     return g_try_malloc_n(1, size);
 227 }
 228
 229 void *g_try_malloc0(size_t size)
 230 {
 231     return g_try_malloc0_n(1, size);
 232 }
 233
 234 void *g_try_realloc(void *ptr, size_t size)
 235 {
 236     return g_try_realloc_n(ptr, 1, size);
 237 }
 238
 239 /*
 240  * GLib string allocation functions
 241  */
 242
 243 char *g_strdup(const char *s)
 244 {
 245     char *dup;
 246     size_t i;
 247
 248     if (!s) {
 249         return NULL;
 250     }
 251
 252     __coverity_string_null_sink__(s);
 253     __coverity_string_size_sink__(s);
 254     dup = __coverity_alloc_nosize__();
 255     __coverity_mark_as_afm_allocated__(dup, "g_free");
 256     for (i = 0; (dup[i] = s[i]); i++) ;
 257     return dup;
 258 }
 259
 260 char *g_strndup(const char *s, size_t n)
 261 {
 262     char *dup;
 263     size_t i;
 264
 265     __coverity_negative_sink__(n);
 266
 267     if (!s) {
 268         return NULL;
 269     }
 270
 271     dup = g_malloc(n + 1);
 272     for (i = 0; i < n && (dup[i] = s[i]); i++) ;
 273     dup[i] = 0;
 274     return dup;
 275 }
 276
 277 char *g_strdup_printf(const char *format, ...)
 278 {
 279     char ch, *s;
 280     size_t len;
 281
 282     __coverity_string_null_sink__(format);
 283     __coverity_string_size_sink__(format);
 284
 285     ch = *format;
 286
 287     s = __coverity_alloc_nosize__();
 288     __coverity_writeall__(s);
 289     __coverity_mark_as_afm_allocated__(s, "g_free");
 290     return s;
 291 }
 292
 293 char *g_strdup_vprintf(const char *format, va_list ap)
 294 {
 295     char ch, *s;
 296     size_t len;
 297
 298     __coverity_string_null_sink__(format);
 299     __coverity_string_size_sink__(format);
 300
 301     ch = *format;
 302     ch = *(char *)ap;
 303
 304     s = __coverity_alloc_nosize__();
 305     __coverity_writeall__(s);
 306     __coverity_mark_as_afm_allocated__(s, "g_free");
 307
 308     return len;
 309 }
 310
 311 char *g_strconcat(const char *s, ...)
 312 {
 313     char *s;
 314
 315     /*
 316      * Can't model: last argument must be null, the others
 317      * null-terminated strings
 318      */
 319
 320     s = __coverity_alloc_nosize__();
 321     __coverity_writeall__(s);
 322     __coverity_mark_as_afm_allocated__(s, "g_free");
 323     return s;
 324 }
 325
 326 /* Other glib functions */
 327
 328 typedef struct _GIOChannel GIOChannel;
 329 GIOChannel *g_io_channel_unix_new(int fd)
 330 {
 331     GIOChannel *c = g_malloc0(sizeof(GIOChannel));
 332     __coverity_escape__(fd);
 333     return c;
 334 }
 335
 336 void g_assertion_message_expr(const char     *domain,
 337                               const char     *file,
 338                               int             line,
 339                               const char     *func,
 340                               const char     *expr)
 341 {
 342     __coverity_panic__();
 343 }