* include/linux/fortify-string.h:562:4: error: call to '__write_overflow' declared with attribute error: detected write beyond size of object (1st parameter)
@ 2026-09-27 22:30 kernel test robot
0 siblings, 0 replies; only message in thread
From: kernel test robot @ 2026-09-27 22:30 UTC (permalink / raw)
To: Lijo Lazar; +Cc: oe-kbuild-all, linux-kernel, Alex Deucher, Hawking Zhang
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 72d3fcf802c45d00b300f25b848a93c3a2bd7c7e
commit: 294403fde5ba8e972d1bab88ea56be0fa2ff1f3e drm/amdgpu: bounds check VBIOS name extraction
date: 3 months ago
config: powerpc-randconfig-r2300-20260927 (https://download.01.org/0day-ci/archive/20260928/202609280038.eX20jfbs-lkp@intel.com/config)
compiler: powerpc-linux-gcc (GCC) 9.5.0
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260928/202609280038.eX20jfbs-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Fixes: 294403fde5ba ("drm/amdgpu: bounds check VBIOS name extraction")
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202609280038.eX20jfbs-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from include/linux/string.h:386,
from include/linux/bitmap.h:13,
from include/linux/cpumask.h:11,
from include/linux/smp.h:13,
from include/linux/lockdep.h:14,
from include/linux/spinlock.h:63,
from include/linux/mmzone.h:8,
from include/linux/gfp.h:7,
from include/linux/umh.h:4,
from include/linux/kmod.h:9,
from include/linux/module.h:18,
from drivers/gpu/drm/amd/amdgpu/atom.c:25:
In function 'fortify_memcpy_chk',
inlined from 'atom_get_vbios_name' at drivers/gpu/drm/amd/amdgpu/atom.c:1404:2,
inlined from 'amdgpu_atom_parse' at drivers/gpu/drm/amd/amdgpu/atom.c:1642:2:
>> include/linux/fortify-string.h:562:4: error: call to '__write_overflow' declared with attribute error: detected write beyond size of object (1st parameter)
562 | __write_overflow();
| ^~~~~~~~~~~~~~~~~~
include/linux/fortify-string.h:569:4: warning: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
569 | __write_overflow_field(p_size_field, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
vim +/__write_overflow +562 include/linux/fortify-string.h
a28a6e860c6cf2 Francis Laniel 2021-02-25 513
f68f2ff91512c1 Kees Cook 2021-04-20 514 /*
f68f2ff91512c1 Kees Cook 2021-04-20 515 * To make sure the compiler can enforce protection against buffer overflows,
f68f2ff91512c1 Kees Cook 2021-04-20 516 * memcpy(), memmove(), and memset() must not be used beyond individual
f68f2ff91512c1 Kees Cook 2021-04-20 517 * struct members. If you need to copy across multiple members, please use
f68f2ff91512c1 Kees Cook 2021-04-20 518 * struct_group() to create a named mirror of an anonymous struct union.
f68f2ff91512c1 Kees Cook 2021-04-20 519 * (e.g. see struct sk_buff.) Read overflow checking is currently only
f68f2ff91512c1 Kees Cook 2021-04-20 520 * done when a write overflow is also present, or when building with W=1.
f68f2ff91512c1 Kees Cook 2021-04-20 521 *
f68f2ff91512c1 Kees Cook 2021-04-20 522 * Mitigation coverage matrix
f68f2ff91512c1 Kees Cook 2021-04-20 523 * Bounds checking at:
f68f2ff91512c1 Kees Cook 2021-04-20 524 * +-------+-------+-------+-------+
f68f2ff91512c1 Kees Cook 2021-04-20 525 * | Compile time | Run time |
f68f2ff91512c1 Kees Cook 2021-04-20 526 * memcpy() argument sizes: | write | read | write | read |
f68f2ff91512c1 Kees Cook 2021-04-20 527 * dest source length +-------+-------+-------+-------+
f68f2ff91512c1 Kees Cook 2021-04-20 528 * memcpy(known, known, constant) | y | y | n/a | n/a |
f68f2ff91512c1 Kees Cook 2021-04-20 529 * memcpy(known, unknown, constant) | y | n | n/a | V |
f68f2ff91512c1 Kees Cook 2021-04-20 530 * memcpy(known, known, dynamic) | n | n | B | B |
f68f2ff91512c1 Kees Cook 2021-04-20 531 * memcpy(known, unknown, dynamic) | n | n | B | V |
f68f2ff91512c1 Kees Cook 2021-04-20 532 * memcpy(unknown, known, constant) | n | y | V | n/a |
f68f2ff91512c1 Kees Cook 2021-04-20 533 * memcpy(unknown, unknown, constant) | n | n | V | V |
f68f2ff91512c1 Kees Cook 2021-04-20 534 * memcpy(unknown, known, dynamic) | n | n | V | B |
f68f2ff91512c1 Kees Cook 2021-04-20 535 * memcpy(unknown, unknown, dynamic) | n | n | V | V |
f68f2ff91512c1 Kees Cook 2021-04-20 536 * +-------+-------+-------+-------+
f68f2ff91512c1 Kees Cook 2021-04-20 537 *
f68f2ff91512c1 Kees Cook 2021-04-20 538 * y = perform deterministic compile-time bounds checking
f68f2ff91512c1 Kees Cook 2021-04-20 539 * n = cannot perform deterministic compile-time bounds checking
f68f2ff91512c1 Kees Cook 2021-04-20 540 * n/a = no run-time bounds checking needed since compile-time deterministic
f68f2ff91512c1 Kees Cook 2021-04-20 541 * B = can perform run-time bounds checking (currently unimplemented)
f68f2ff91512c1 Kees Cook 2021-04-20 542 * V = vulnerable to run-time overflow (will need refactoring to solve)
f68f2ff91512c1 Kees Cook 2021-04-20 543 *
f68f2ff91512c1 Kees Cook 2021-04-20 544 */
54d9469bc515dc Kees Cook 2021-06-24 545 __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
f68f2ff91512c1 Kees Cook 2021-04-20 546 const size_t p_size,
f68f2ff91512c1 Kees Cook 2021-04-20 547 const size_t q_size,
f68f2ff91512c1 Kees Cook 2021-04-20 548 const size_t p_size_field,
f68f2ff91512c1 Kees Cook 2021-04-20 549 const size_t q_size_field,
475ddf1fce1ec4 Kees Cook 2023-04-07 550 const u8 func)
a28a6e860c6cf2 Francis Laniel 2021-02-25 551 {
a28a6e860c6cf2 Francis Laniel 2021-02-25 552 if (__builtin_constant_p(size)) {
f68f2ff91512c1 Kees Cook 2021-04-20 553 /*
f68f2ff91512c1 Kees Cook 2021-04-20 554 * Length argument is a constant expression, so we
f68f2ff91512c1 Kees Cook 2021-04-20 555 * can perform compile-time bounds checking where
fa35198f39571b Kees Cook 2022-09-19 556 * buffer sizes are also known at compile time.
f68f2ff91512c1 Kees Cook 2021-04-20 557 */
f68f2ff91512c1 Kees Cook 2021-04-20 558
f68f2ff91512c1 Kees Cook 2021-04-20 559 /* Error when size is larger than enclosing struct. */
fa35198f39571b Kees Cook 2022-09-19 560 if (__compiletime_lessthan(p_size_field, p_size) &&
fa35198f39571b Kees Cook 2022-09-19 561 __compiletime_lessthan(p_size, size))
a28a6e860c6cf2 Francis Laniel 2021-02-25 @562 __write_overflow();
fa35198f39571b Kees Cook 2022-09-19 563 if (__compiletime_lessthan(q_size_field, q_size) &&
fa35198f39571b Kees Cook 2022-09-19 564 __compiletime_lessthan(q_size, size))
a28a6e860c6cf2 Francis Laniel 2021-02-25 565 __read_overflow2();
f68f2ff91512c1 Kees Cook 2021-04-20 566
f68f2ff91512c1 Kees Cook 2021-04-20 567 /* Warn when write size argument larger than dest field. */
fa35198f39571b Kees Cook 2022-09-19 568 if (__compiletime_lessthan(p_size_field, size))
f68f2ff91512c1 Kees Cook 2021-04-20 569 __write_overflow_field(p_size_field, size);
f68f2ff91512c1 Kees Cook 2021-04-20 570 /*
f68f2ff91512c1 Kees Cook 2021-04-20 571 * Warn for source field over-read when building with W=1
f68f2ff91512c1 Kees Cook 2021-04-20 572 * or when an over-write happened, so both can be fixed at
f68f2ff91512c1 Kees Cook 2021-04-20 573 * the same time.
f68f2ff91512c1 Kees Cook 2021-04-20 574 */
fa35198f39571b Kees Cook 2022-09-19 575 if ((IS_ENABLED(KBUILD_EXTRA_WARN1) ||
fa35198f39571b Kees Cook 2022-09-19 576 __compiletime_lessthan(p_size_field, size)) &&
fa35198f39571b Kees Cook 2022-09-19 577 __compiletime_lessthan(q_size_field, size))
f68f2ff91512c1 Kees Cook 2021-04-20 578 __read_overflow2_field(q_size_field, size);
a28a6e860c6cf2 Francis Laniel 2021-02-25 579 }
f68f2ff91512c1 Kees Cook 2021-04-20 580 /*
f68f2ff91512c1 Kees Cook 2021-04-20 581 * At this point, length argument may not be a constant expression,
f68f2ff91512c1 Kees Cook 2021-04-20 582 * so run-time bounds checking can be done where buffer sizes are
f68f2ff91512c1 Kees Cook 2021-04-20 583 * known. (This is not an "else" because the above checks may only
f68f2ff91512c1 Kees Cook 2021-04-20 584 * be compile-time warnings, and we want to still warn for run-time
f68f2ff91512c1 Kees Cook 2021-04-20 585 * overflows.)
f68f2ff91512c1 Kees Cook 2021-04-20 586 */
f68f2ff91512c1 Kees Cook 2021-04-20 587
f68f2ff91512c1 Kees Cook 2021-04-20 588 /*
f68f2ff91512c1 Kees Cook 2021-04-20 589 * Always stop accesses beyond the struct that contains the
f68f2ff91512c1 Kees Cook 2021-04-20 590 * field, when the buffer's remaining size is known.
311fb40aa0569a Kees Cook 2022-09-02 591 * (The SIZE_MAX test is to optimize away checks where the buffer
f68f2ff91512c1 Kees Cook 2021-04-20 592 * lengths are unknown.)
f68f2ff91512c1 Kees Cook 2021-04-20 593 */
475ddf1fce1ec4 Kees Cook 2023-04-07 594 if (p_size != SIZE_MAX && p_size < size)
3d965b33e40d97 Kees Cook 2023-04-07 595 fortify_panic(func, FORTIFY_WRITE, p_size, size, true);
475ddf1fce1ec4 Kees Cook 2023-04-07 596 else if (q_size != SIZE_MAX && q_size < size)
94fd44648dae2a Kees Cook 2025-07-29 597 fortify_panic(func, FORTIFY_READ, q_size, size, true);
54d9469bc515dc Kees Cook 2021-06-24 598
54d9469bc515dc Kees Cook 2021-06-24 599 /*
54d9469bc515dc Kees Cook 2021-06-24 600 * Warn when writing beyond destination field size.
54d9469bc515dc Kees Cook 2021-06-24 601 *
2003e483a81cc2 Kees Cook 2024-06-19 602 * Note the implementation of __builtin_*object_size() behaves
54d9469bc515dc Kees Cook 2021-06-24 603 * like sizeof() when not directly referencing a flexible
54d9469bc515dc Kees Cook 2021-06-24 604 * array member, which means there will be many bounds checks
54d9469bc515dc Kees Cook 2021-06-24 605 * that will appear at run-time, without a way for them to be
54d9469bc515dc Kees Cook 2021-06-24 606 * detected at compile-time (as can be done when the destination
54d9469bc515dc Kees Cook 2021-06-24 607 * is specifically the flexible array member).
54d9469bc515dc Kees Cook 2021-06-24 608 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832
54d9469bc515dc Kees Cook 2021-06-24 609 */
2003e483a81cc2 Kees Cook 2024-06-19 610 if (p_size_field != SIZE_MAX &&
54d9469bc515dc Kees Cook 2021-06-24 611 p_size != p_size_field && p_size_field < size)
54d9469bc515dc Kees Cook 2021-06-24 612 return true;
54d9469bc515dc Kees Cook 2021-06-24 613
54d9469bc515dc Kees Cook 2021-06-24 614 return false;
a28a6e860c6cf2 Francis Laniel 2021-02-25 615 }
a28a6e860c6cf2 Francis Laniel 2021-02-25 616
:::::: The code at line 562 was first introduced by commit
:::::: a28a6e860c6cf231cf3c5171c75c342adcd00406 string.h: move fortified functions definitions in a dedicated header.
:::::: TO: Francis Laniel <laniel_francis@privacyrequired.com>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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