| 1 | // **************************************************************************** |
| 2 | // Prelude |
| 3 | // **************************************************************************** |
| 4 | |
| 5 | // Note: some isomorphisms are handled in the engine directly because they |
| 6 | // require special support. They can not be easily described with a |
| 7 | // XX <=> YY. But some of them have names, so they can be disabled, as for |
| 8 | // any other isomorphism rule. That also means that those names can not |
| 9 | // be used for regular isomorphism rule. Those reserved rule names are: |
| 10 | // - optional_storage |
| 11 | // - optional_qualifier |
| 12 | // - value_format |
| 13 | // See parse_cocci.ml, pattern.ml, transformation.ml. |
| 14 | |
| 15 | |
| 16 | // Note: the order of the rules has some importance. As we don't do a fixpoint, |
| 17 | // changing the order may impact the result. For instance, if we have |
| 18 | // |
| 19 | // iso1 = x+y <=> y+x |
| 20 | // iso2 = i++ <=> i=i+1; |
| 21 | // |
| 22 | // and if |
| 23 | // in SP we have i++; |
| 24 | // in C we have i=1+i; |
| 25 | // |
| 26 | // Does the SP matches the C ? |
| 27 | // - Yes if iso2 precedes iso1 in this file, |
| 28 | // - No otherwise. |
| 29 | |
| 30 | |
| 31 | // **************************************************************************** |
| 32 | // Standard C isomorphisms |
| 33 | // **************************************************************************** |
| 34 | |
| 35 | // --------------------------------------------------------------------------- |
| 36 | // Spacing (include comments) isomorphisms |
| 37 | // --------------------------------------------------------------------------- |
| 38 | // They are handled at lex time. |
| 39 | |
| 40 | // --------------------------------------------------------------------------- |
| 41 | // Dataflow isomorphisms (copy propagation, assignments) |
| 42 | // --------------------------------------------------------------------------- |
| 43 | // They are handled in engine (TODO). |
| 44 | |
| 45 | |
| 46 | // --------------------------------------------------------------------------- |
| 47 | // Iso-by-absence (optional qualifier, storage, sign, cast) isomorphisms |
| 48 | // --------------------------------------------------------------------------- |
| 49 | // Some of them are handled in cocci_vs_c. Some of them handled here. |
| 50 | |
| 51 | |
| 52 | // We would like that |
| 53 | // chip = (ak4117_t *)snd_magic_kcalloc(ak4117_t, 0, GFP_KERNEL); |
| 54 | // also matches |
| 55 | // X = snd_magic_kcalloc(T, 0, C) |
| 56 | // |
| 57 | // For the moment because the iso is (T) E => E and not <=>, it forces |
| 58 | // us to rewrite the SP as X = (T) snd_magic_kcalloc(T, 0, C) |
| 59 | |
| 60 | Expression |
| 61 | @ drop_cast @ |
| 62 | expression E; |
| 63 | pure type T; |
| 64 | @@ |
| 65 | |
| 66 | // in the following, the space at the beginning of the line is very important! |
| 67 | (T)E => E |
| 68 | |
| 69 | Type |
| 70 | @ add_signed @ |
| 71 | @@ |
| 72 | int => signed int |
| 73 | |
| 74 | Type |
| 75 | @ add_int1 @ |
| 76 | @@ |
| 77 | unsigned => unsigned int |
| 78 | |
| 79 | Type |
| 80 | @ add_int2 @ |
| 81 | @@ |
| 82 | signed => signed int |
| 83 | |
| 84 | |
| 85 | // --------------------------------------------------------------------------- |
| 86 | // Field isomorphisms |
| 87 | // --------------------------------------------------------------------------- |
| 88 | // Dereferences |
| 89 | |
| 90 | |
| 91 | // Those iso were introduced for the 'generic program matching' paper, |
| 92 | // with sgrep. The idea is that when we want to detect bugs, |
| 93 | // we want to detect something like free(X) ... *X |
| 94 | // meaning that you try to access something that have been freed. |
| 95 | // But *X is not the only way to deference X, there is also |
| 96 | // X->fld, hence those iso. |
| 97 | |
| 98 | // The following don't see like a good idea, because eg fld could be |
| 99 | // instantiated in different ways in different places, meaning that the |
| 100 | // two occurrences of "*E" would not refer to the same thing at all. |
| 101 | // This could be addressed by making E pure, but then I think it would |
| 102 | // have no purpose. |
| 103 | |
| 104 | // Expression |
| 105 | // @@ |
| 106 | // expression E; |
| 107 | // identifier fld; |
| 108 | // @@ |
| 109 | // |
| 110 | // *E => E->fld |
| 111 | // |
| 112 | // Expression |
| 113 | // @@ |
| 114 | // expression E; |
| 115 | // identifier fld; |
| 116 | // @@ |
| 117 | // |
| 118 | // *E => (E)->fld |
| 119 | // |
| 120 | // Expression |
| 121 | // @@ |
| 122 | // expression E,E1; |
| 123 | // @@ |
| 124 | // |
| 125 | // *E => E[E1] |
| 126 | |
| 127 | // --------------------------------------------------------------------------- |
| 128 | // Typedef isomorphisms |
| 129 | // --------------------------------------------------------------------------- |
| 130 | // They are handled in engine. |
| 131 | |
| 132 | |
| 133 | // --------------------------------------------------------------------------- |
| 134 | // Boolean isomorphisms for int and pointer types |
| 135 | // --------------------------------------------------------------------------- |
| 136 | |
| 137 | // the space at the beginning of the line is very important! |
| 138 | Expression |
| 139 | @ not_int1 @ |
| 140 | int X; |
| 141 | @@ |
| 142 | !X => X == 0 |
| 143 | |
| 144 | TestExpression |
| 145 | @ not_int2 @ |
| 146 | int X; |
| 147 | @@ |
| 148 | X => X != 0 |
| 149 | |
| 150 | // the space at the beginning of the line is very important! |
| 151 | Expression |
| 152 | @ not_ptr1 @ |
| 153 | expression *X; |
| 154 | @@ |
| 155 | !X => X == NULL |
| 156 | |
| 157 | TestExpression |
| 158 | @ not_ptr2 @ |
| 159 | expression *X; |
| 160 | @@ |
| 161 | X => X != NULL |
| 162 | |
| 163 | // --------------------------------------------------------------------------- |
| 164 | // Boolean isomorphisms |
| 165 | // --------------------------------------------------------------------------- |
| 166 | |
| 167 | Expression |
| 168 | @commeq@ |
| 169 | expression E; |
| 170 | constant C; |
| 171 | @@ |
| 172 | |
| 173 | E == C <=> C == E |
| 174 | |
| 175 | Expression |
| 176 | @commneq@ |
| 177 | expression E; |
| 178 | constant C; |
| 179 | @@ |
| 180 | |
| 181 | E != C <=> C != E |
| 182 | |
| 183 | Expression |
| 184 | @ is_zero @ |
| 185 | expression X; |
| 186 | @@ |
| 187 | X == 0 => !X |
| 188 | |
| 189 | // X should be a test expression, but X!=0 doesn't have to be one |
| 190 | // not nice at all... ToTestExpression sets everything after the first |
| 191 | // pattern in the iso rule to be TestExpression |
| 192 | ToTestExpression |
| 193 | @ isnt_zero @ |
| 194 | expression X; |
| 195 | @@ |
| 196 | X != 0 => X |
| 197 | |
| 198 | Expression |
| 199 | @ is_null @ |
| 200 | expression X; |
| 201 | @@ |
| 202 | X == NULL => !X |
| 203 | |
| 204 | ToTestExpression |
| 205 | @ isnt_null1 @ |
| 206 | expression X; |
| 207 | @@ |
| 208 | X != NULL => X |
| 209 | |
| 210 | // --------------------------------------------------------------------------- |
| 211 | // Bit operations |
| 212 | // --------------------------------------------------------------------------- |
| 213 | |
| 214 | Expression |
| 215 | @ bitor_comm @ |
| 216 | expression X,Y; |
| 217 | @@ |
| 218 | X | Y => Y | X |
| 219 | |
| 220 | Expression |
| 221 | @ bitand_comm @ |
| 222 | expression X,Y; |
| 223 | @@ |
| 224 | X & Y => Y & X |
| 225 | |
| 226 | // only if side effect free in theory, perhaps makes no sense |
| 227 | // Expression |
| 228 | // @ and_comm @ |
| 229 | // expression X,Y; |
| 230 | // @@ |
| 231 | // X && Y => Y && X |
| 232 | |
| 233 | // Expression |
| 234 | // @ or_comm @ |
| 235 | // expression X,Y; |
| 236 | // @@ |
| 237 | // X || Y => Y || X |
| 238 | |
| 239 | |
| 240 | // --------------------------------------------------------------------------- |
| 241 | // Arithmetic isomorphisms |
| 242 | // --------------------------------------------------------------------------- |
| 243 | //todo: require check side-effect free expression |
| 244 | |
| 245 | Expression |
| 246 | @ plus_comm @ |
| 247 | expression X, Y; |
| 248 | @@ |
| 249 | X + Y => Y + X |
| 250 | |
| 251 | |
| 252 | // needed in kcalloc CE, where have a -kzalloc(c * sizeof(T), E) |
| 253 | Expression |
| 254 | @ mult_comm @ |
| 255 | expression X, Y; |
| 256 | @@ |
| 257 | X * Y => Y * X |
| 258 | |
| 259 | Expression |
| 260 | @ plus_assoc @ |
| 261 | expression X, Y, Z; |
| 262 | @@ |
| 263 | // note space before ( |
| 264 | (X + Y) + Z <=> X + Y + Z |
| 265 | |
| 266 | Expression |
| 267 | @ minus_assoc @ |
| 268 | expression X, Y, Z; |
| 269 | @@ |
| 270 | |
| 271 | (X - Y) - Z <=> X - Y - Z |
| 272 | |
| 273 | Expression |
| 274 | @ plus_minus_assoc1 @ |
| 275 | expression X, Y, Z; |
| 276 | @@ |
| 277 | |
| 278 | (X + Y) - Z <=> X + Y - Z |
| 279 | |
| 280 | Expression |
| 281 | @ plus_minus_assoc2 @ |
| 282 | expression X, Y, Z; |
| 283 | @@ |
| 284 | |
| 285 | (X - Y) + Z <=> X - Y + Z |
| 286 | |
| 287 | Expression |
| 288 | @ times_assoc @ |
| 289 | expression X, Y, Z; |
| 290 | @@ |
| 291 | |
| 292 | (X * Y) * Z <=> X * Y * Z |
| 293 | |
| 294 | Expression |
| 295 | @ div_assoc @ |
| 296 | expression X, Y, Z; |
| 297 | @@ |
| 298 | |
| 299 | (X / Y) / Z <=> X / Y / Z |
| 300 | |
| 301 | Expression |
| 302 | @ times_div_assoc1 @ |
| 303 | expression X, Y, Z; |
| 304 | @@ |
| 305 | |
| 306 | (X * Y) / Z <=> X * Y / Z |
| 307 | |
| 308 | Expression |
| 309 | @ times_div_assoc2 @ |
| 310 | expression X, Y, Z; |
| 311 | @@ |
| 312 | |
| 313 | (X / Y) * Z <=> X / Y * Z |
| 314 | |
| 315 | // --------------------------------------------------------------------------- |
| 316 | // Relational isomorphisms |
| 317 | // --------------------------------------------------------------------------- |
| 318 | |
| 319 | Expression |
| 320 | @ gtr_lss @ |
| 321 | expression X, Y; |
| 322 | @@ |
| 323 | X < Y <=> Y > X |
| 324 | |
| 325 | Expression |
| 326 | @ gtr_lss_eq @ |
| 327 | expression X, Y; |
| 328 | @@ |
| 329 | X <= Y <=> Y >= X |
| 330 | |
| 331 | // --------------------------------------------------------------------------- |
| 332 | // Increment isomorphisms |
| 333 | // --------------------------------------------------------------------------- |
| 334 | |
| 335 | // equivalences between i++, +=1, etc. |
| 336 | // note: there is an addition in this SP. |
| 337 | Statement |
| 338 | @ inc @ |
| 339 | identifier i; |
| 340 | @@ |
| 341 | i++; <=> ++i; <=> i+=1; <=> i=i+1; |
| 342 | |
| 343 | // I would like to avoid the following rule, but we cant transform a ++i |
| 344 | // in i++ everywhere. We can do it only when the instruction is alone, |
| 345 | // such as when there is not stuff around it (not as in x = i++) That's why in |
| 346 | // the previous iso, we have explicitely force the i++ do be alone with |
| 347 | // the ';'. But unfortunately in the last expression of the for there is |
| 348 | // no ';' so the previous rule cannot be applied, hence this special |
| 349 | // case. |
| 350 | |
| 351 | Statement |
| 352 | @ for_inc @ |
| 353 | expression X, Y; |
| 354 | statement S; |
| 355 | identifier i; |
| 356 | @@ |
| 357 | for(X;Y;i++) S <=> for(X;Y;++i) S |
| 358 | |
| 359 | |
| 360 | // **************************************************************************** |
| 361 | // gcc specific isomorphisms |
| 362 | // **************************************************************************** |
| 363 | |
| 364 | // likely and unlikely are used to give hints to gcc to improve performance. |
| 365 | |
| 366 | Expression |
| 367 | @ unlikely @ |
| 368 | expression E; |
| 369 | @@ |
| 370 | |
| 371 | unlikely(E) <=> likely(E) => E |
| 372 | |
| 373 | // --------------------------------------------------------------------------- |
| 374 | // Parenthesis isomorphisms |
| 375 | // --------------------------------------------------------------------------- |
| 376 | //Expression |
| 377 | //@@ expression E; @@ |
| 378 | // E => (E) |
| 379 | //// E => ((E)) |
| 380 | |
| 381 | // todo: isomorphism avec les () around ? cf sizeof 3. |
| 382 | // (E) => E with some conditions. |
| 383 | |
| 384 | Expression |
| 385 | @ paren @ |
| 386 | expression E; |
| 387 | @@ |
| 388 | |
| 389 | (E) => E |
| 390 | |
| 391 | // --------------------------------------------------------------------------- |
| 392 | // Statement isomorphisms |
| 393 | // --------------------------------------------------------------------------- |
| 394 | |
| 395 | // --------------------------------------------------------------------------- |
| 396 | // Value isomorphisms |
| 397 | // --------------------------------------------------------------------------- |
| 398 | |
| 399 | // There is also equal_c_int in cocci_vs_c to dealing with other |
| 400 | // integer decimal/hexadecimal isomorphisms. |
| 401 | // an argexpression applies only at top level, in the argument of a |
| 402 | // function call, or on the right-hand side of an assignment |
| 403 | ArgExpression |
| 404 | @ zero_multiple_format @ |
| 405 | @@ |
| 406 | 0 => '\0' |
| 407 | |
| 408 | // ---------------- |
| 409 | // If |
| 410 | // ---------------- |
| 411 | |
| 412 | // **************************************************************************** |
| 413 | // if structure isomorphisms |
| 414 | // **************************************************************************** |
| 415 | |
| 416 | // these are after the above so that the introduced negation will distribute |
| 417 | // properly over the argument to likely/unlikely |
| 418 | |
| 419 | Statement |
| 420 | @ neg_if @ |
| 421 | expression X; |
| 422 | statement S1, S2; |
| 423 | @@ |
| 424 | if (X) S1 else S2 => if (!X) S2 else S1 |
| 425 | |
| 426 | Statement |
| 427 | @ ne_if @ |
| 428 | expression E1, E2; |
| 429 | statement S1, S2; |
| 430 | @@ |
| 431 | if (E1 != E2) S1 else S2 => if (E1 == E2) S2 else S1 |
| 432 | |
| 433 | Statement |
| 434 | @ drop_else @ |
| 435 | expression E; |
| 436 | statement S1; |
| 437 | pure statement S2; |
| 438 | @@ |
| 439 | |
| 440 | if (E) S1 else S2 => if (E) S1 |
| 441 | |
| 442 | Expression |
| 443 | @ neg_if_exp @ |
| 444 | expression E1, E2, E3; |
| 445 | @@ |
| 446 | |
| 447 | E1 ? E2 : E3 => !E1 ? E3 : E2 |
| 448 | |
| 449 | |
| 450 | // if (X) Y else Z <=> X ? Y : Z sometimes. |
| 451 | |
| 452 | // ---------------- |
| 453 | // Loops |
| 454 | // ---------------- |
| 455 | |
| 456 | // --------------------------------------------------------------------------- |
| 457 | // Optional initializers |
| 458 | // --------------------------------------------------------------------------- |
| 459 | // this is not safe when the declaration is replaced |
| 460 | // attempt to indicate that by requiring that Z is context |
| 461 | // no optional static/extern for isos |
| 462 | Declaration |
| 463 | @ decl_init @ |
| 464 | type T; |
| 465 | context identifier Z; |
| 466 | @@ |
| 467 | T Z; => T Z = ...; |
| 468 | |
| 469 | Declaration |
| 470 | @ const_decl_init @ |
| 471 | type T; |
| 472 | identifier Z; |
| 473 | constant C; |
| 474 | @@ |
| 475 | T Z; => T Z = C; |
| 476 | |
| 477 | Declaration |
| 478 | @ extern_decl_init @ |
| 479 | type T; |
| 480 | context identifier Z; |
| 481 | @@ |
| 482 | extern T Z; => extern T Z = ...; |
| 483 | |
| 484 | Declaration |
| 485 | @ const_extern_decl_init @ |
| 486 | type T; |
| 487 | identifier Z; |
| 488 | constant C; |
| 489 | @@ |
| 490 | extern T Z; => extern T Z = C; |
| 491 | |
| 492 | Declaration |
| 493 | @ static_decl_init @ |
| 494 | type T; |
| 495 | context identifier Z; |
| 496 | @@ |
| 497 | static T Z; => static T Z = ...; |
| 498 | |
| 499 | Declaration |
| 500 | @ const_static_decl_init @ |
| 501 | type T; |
| 502 | identifier Z; |
| 503 | constant C; |
| 504 | @@ |
| 505 | static T Z; => static T Z = C; |
| 506 | |
| 507 | // --------------------------------------------------------------------------- |
| 508 | // Branch (or compound) isomorphisms |
| 509 | // --------------------------------------------------------------------------- |
| 510 | // maybe a cocci patch should require something that looks like what is on |
| 511 | // the left above to occur in a if or while |
| 512 | |
| 513 | // could worry that this has to be a simple statement, but this should work |
| 514 | // better as it allows + code on S |
| 515 | Statement |
| 516 | @ braces1 @ |
| 517 | statement S; |
| 518 | @@ |
| 519 | { ... S } => S |
| 520 | |
| 521 | Statement |
| 522 | @ braces2 @ |
| 523 | statement S; |
| 524 | @@ |
| 525 | { ... S ... } => S |
| 526 | |
| 527 | Statement |
| 528 | @ braces3 @ |
| 529 | statement S; |
| 530 | @@ |
| 531 | { S ... } => S |
| 532 | |
| 533 | Statement |
| 534 | @ braces4 @ |
| 535 | statement S; |
| 536 | @@ |
| 537 | { S } => S |
| 538 | |
| 539 | Statement |
| 540 | @ ret @ |
| 541 | @@ |
| 542 | return ...; => return; |
| 543 | |
| 544 | |
| 545 | // --------------------------------------------------------------------------- |
| 546 | // Declaration isomorphisms |
| 547 | // --------------------------------------------------------------------------- |
| 548 | // They are handled in engine (TODO) |
| 549 | |
| 550 | // int i,j,k; <=> int i; int j; int k; |
| 551 | |
| 552 | |
| 553 | // --------------------------------------------------------------------------- |
| 554 | // Affectation/initialisation isomorphism |
| 555 | // --------------------------------------------------------------------------- |
| 556 | // They are handled in engine. |
| 557 | // 'X = Y' should also match 'type X = Y'; |
| 558 | |
| 559 | // --------------------------------------------------------------------------- |
| 560 | // Pointer/Array isomorphisms |
| 561 | // --------------------------------------------------------------------------- |
| 562 | |
| 563 | // pointer arithmetic equivalences |
| 564 | // a + x <=> a[x] |
| 565 | |
| 566 | // --------------------------------------------------------------------------- |
| 567 | // Pointer/Field isomorphisms |
| 568 | // --------------------------------------------------------------------------- |
| 569 | |
| 570 | Expression |
| 571 | @ ptr_to_array @ |
| 572 | expression E1, E2; // was pure, not sure why that's needed, not good for rule27 |
| 573 | identifier fld; |
| 574 | @@ |
| 575 | |
| 576 | E1->fld => E1[E2].fld |
| 577 | |
| 578 | |
| 579 | |
| 580 | TopLevel |
| 581 | @ mkinit @ |
| 582 | type T; |
| 583 | pure context T E; |
| 584 | identifier I; |
| 585 | identifier fld; |
| 586 | expression E1; |
| 587 | @@ |
| 588 | |
| 589 | E.fld = E1; => T I = { .fld = E1, }; |
| 590 | |
| 591 | // --------------------------------------------------------------------------- |
| 592 | // more pointer field iso |
| 593 | // --------------------------------------------------------------------------- |
| 594 | |
| 595 | // pure means that either the whole field reference expression is dropped, |
| 596 | // or E is context code and has no attached + code |
| 597 | // not really... pure means matches a unitary unplussed metavariable |
| 598 | // but this rule doesn't work anyway |
| 599 | |
| 600 | Expression |
| 601 | @ fld_to_ptr @ |
| 602 | type T; |
| 603 | pure T E; |
| 604 | pure T *E1; |
| 605 | identifier fld; |
| 606 | @@ |
| 607 | |
| 608 | E.fld => E1->fld |
| 609 | |
| 610 | |
| 611 | // --------------------------------------------------------------------------- |
| 612 | // sizeof isomorphisms |
| 613 | // --------------------------------------------------------------------------- |
| 614 | |
| 615 | // The following is made redundant by the paren isomorphism |
| 616 | // Expression |
| 617 | // @ sizeof_parens @ |
| 618 | // expression E; |
| 619 | // @@ |
| 620 | |
| 621 | // sizeof(E) => sizeof E |
| 622 | |
| 623 | |
| 624 | Expression |
| 625 | @ sizeof_type_expr @ |
| 626 | pure type T; // pure because we drop a metavar |
| 627 | T E; |
| 628 | @@ |
| 629 | |
| 630 | sizeof(T) => sizeof(E) |
| 631 | |
| 632 | // Expression |
| 633 | // @ fld_func_call @ |
| 634 | // expression list ES; |
| 635 | // identifier fld; |
| 636 | // expression E; |
| 637 | // @@ |
| 638 | // E.fld(ES) <=> (*E.fld)(ES) |
| 639 | |
| 640 | |
| 641 | // **************************************************************************** |
| 642 | // Linux specific isomorphisms |
| 643 | // **************************************************************************** |
| 644 | |
| 645 | // Examples: many functions are equivalent/related, and one SP modifying |
| 646 | // such a function should also modify the equivalent/related one. |
| 647 | |
| 648 | |
| 649 | // --------------------------------------------------------------------------- |
| 650 | // in rule18, needed ? |
| 651 | // --------------------------------------------------------------------------- |
| 652 | // ( |
| 653 | // - test_and_set_bit(ev, &bcs->event); |
| 654 | // | |
| 655 | // - set_bit(ev, &bcs->event); |
| 656 | // | |
| 657 | // - bcs->event |= 1 << ev; // the only case that is used |
| 658 | |
| 659 | |
| 660 | // **************************************************************************** |
| 661 | // Everything that is required to be in last position, for ugly reasons ... |
| 662 | // **************************************************************************** |