include/linux/fortify-string.h:520:4: warning: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()?

From: kernel test robot
Date: Tue Feb 28 2023 - 11:56:38 EST

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tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: ae3419fbac845b4d3f3a9fae4cc80c68d82cdf6e
commit: 439a1bcac648fe9b59210cde8991fb2acf37bdab fortify: Use __builtin_dynamic_object_size() when available
date: 8 weeks ago
config: s390-randconfig-r034-20230227 (https://download.01.org/0day-ci/archive/20230301/202303010005.KqCMLzYH-lkp@xxxxxxxxx/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project db89896bbbd2251fff457699635acbbedeead27f)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install s390 cross compiling tool for clang build
# apt-get install binutils-s390x-linux-gnu
# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=439a1bcac648fe9b59210cde8991fb2acf37bdab
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout 439a1bcac648fe9b59210cde8991fb2acf37bdab
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=s390 olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash fs/ksmbd/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Link: https://lore.kernel.org/oe-kbuild-all/202303010005.KqCMLzYH-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

In file included from fs/ksmbd/smb_common.c:13:
In file included from fs/ksmbd/connection.h:10:
In file included from include/linux/ip.h:16:
In file included from include/linux/skbuff.h:31:
In file included from include/linux/dma-mapping.h:10:
In file included from include/linux/scatterlist.h:9:
In file included from arch/s390/include/asm/io.h:75:
include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __raw_readb(PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
~~~~~~~~~~ ^
include/uapi/linux/byteorder/big_endian.h:37:59: note: expanded from macro '__le16_to_cpu'
#define __le16_to_cpu(x) __swab16((__force __u16)(__le16)(x))
^
include/uapi/linux/swab.h:102:54: note: expanded from macro '__swab16'
#define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
^
In file included from fs/ksmbd/smb_common.c:13:
In file included from fs/ksmbd/connection.h:10:
In file included from include/linux/ip.h:16:
In file included from include/linux/skbuff.h:31:
In file included from include/linux/dma-mapping.h:10:
In file included from include/linux/scatterlist.h:9:
In file included from arch/s390/include/asm/io.h:75:
include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
~~~~~~~~~~ ^
include/uapi/linux/byteorder/big_endian.h:35:59: note: expanded from macro '__le32_to_cpu'
#define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
^
include/uapi/linux/swab.h:115:54: note: expanded from macro '__swab32'
#define __swab32(x) (__u32)__builtin_bswap32((__u32)(x))
^
In file included from fs/ksmbd/smb_common.c:13:
In file included from fs/ksmbd/connection.h:10:
In file included from include/linux/ip.h:16:
In file included from include/linux/skbuff.h:31:
In file included from include/linux/dma-mapping.h:10:
In file included from include/linux/scatterlist.h:9:
In file included from arch/s390/include/asm/io.h:75:
include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writeb(value, PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:692:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
readsb(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:700:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
readsw(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:708:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
readsl(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:717:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
writesb(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:726:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
writesw(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:735:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
writesl(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
In file included from fs/ksmbd/smb_common.c:7:
In file included from include/linux/user_namespace.h:5:
In file included from include/linux/kref.h:16:
In file included from include/linux/spinlock.h:63:
In file included from include/linux/lockdep.h:14:
In file included from include/linux/smp.h:13:
In file included from include/linux/cpumask.h:12:
In file included from include/linux/bitmap.h:11:
In file included from include/linux/string.h:253:
>> include/linux/fortify-string.h:520:4: warning: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
__write_overflow_field(p_size_field, size);
^
13 warnings generated.

vim +520 include/linux/fortify-string.h

a28a6e860c6cf2 Francis Laniel 2021-02-25 464
f68f2ff91512c1 Kees Cook 2021-04-20 465 /*
f68f2ff91512c1 Kees Cook 2021-04-20 466 * To make sure the compiler can enforce protection against buffer overflows,
f68f2ff91512c1 Kees Cook 2021-04-20 467 * memcpy(), memmove(), and memset() must not be used beyond individual
f68f2ff91512c1 Kees Cook 2021-04-20 468 * struct members. If you need to copy across multiple members, please use
f68f2ff91512c1 Kees Cook 2021-04-20 469 * struct_group() to create a named mirror of an anonymous struct union.
f68f2ff91512c1 Kees Cook 2021-04-20 470 * (e.g. see struct sk_buff.) Read overflow checking is currently only
f68f2ff91512c1 Kees Cook 2021-04-20 471 * done when a write overflow is also present, or when building with W=1.
f68f2ff91512c1 Kees Cook 2021-04-20 472 *
f68f2ff91512c1 Kees Cook 2021-04-20 473 * Mitigation coverage matrix
f68f2ff91512c1 Kees Cook 2021-04-20 474 * Bounds checking at:
f68f2ff91512c1 Kees Cook 2021-04-20 475 * +-------+-------+-------+-------+
f68f2ff91512c1 Kees Cook 2021-04-20 476 * | Compile time | Run time |
f68f2ff91512c1 Kees Cook 2021-04-20 477 * memcpy() argument sizes: | write | read | write | read |
f68f2ff91512c1 Kees Cook 2021-04-20 478 * dest source length +-------+-------+-------+-------+
f68f2ff91512c1 Kees Cook 2021-04-20 479 * memcpy(known, known, constant) | y | y | n/a | n/a |
f68f2ff91512c1 Kees Cook 2021-04-20 480 * memcpy(known, unknown, constant) | y | n | n/a | V |
f68f2ff91512c1 Kees Cook 2021-04-20 481 * memcpy(known, known, dynamic) | n | n | B | B |
f68f2ff91512c1 Kees Cook 2021-04-20 482 * memcpy(known, unknown, dynamic) | n | n | B | V |
f68f2ff91512c1 Kees Cook 2021-04-20 483 * memcpy(unknown, known, constant) | n | y | V | n/a |
f68f2ff91512c1 Kees Cook 2021-04-20 484 * memcpy(unknown, unknown, constant) | n | n | V | V |
f68f2ff91512c1 Kees Cook 2021-04-20 485 * memcpy(unknown, known, dynamic) | n | n | V | B |
f68f2ff91512c1 Kees Cook 2021-04-20 486 * memcpy(unknown, unknown, dynamic) | n | n | V | V |
f68f2ff91512c1 Kees Cook 2021-04-20 487 * +-------+-------+-------+-------+
f68f2ff91512c1 Kees Cook 2021-04-20 488 *
f68f2ff91512c1 Kees Cook 2021-04-20 489 * y = perform deterministic compile-time bounds checking
f68f2ff91512c1 Kees Cook 2021-04-20 490 * n = cannot perform deterministic compile-time bounds checking
f68f2ff91512c1 Kees Cook 2021-04-20 491 * n/a = no run-time bounds checking needed since compile-time deterministic
f68f2ff91512c1 Kees Cook 2021-04-20 492 * B = can perform run-time bounds checking (currently unimplemented)
f68f2ff91512c1 Kees Cook 2021-04-20 493 * V = vulnerable to run-time overflow (will need refactoring to solve)
f68f2ff91512c1 Kees Cook 2021-04-20 494 *
f68f2ff91512c1 Kees Cook 2021-04-20 495 */
54d9469bc515dc Kees Cook 2021-06-24 496 __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
f68f2ff91512c1 Kees Cook 2021-04-20 497 const size_t p_size,
f68f2ff91512c1 Kees Cook 2021-04-20 498 const size_t q_size,
f68f2ff91512c1 Kees Cook 2021-04-20 499 const size_t p_size_field,
f68f2ff91512c1 Kees Cook 2021-04-20 500 const size_t q_size_field,
f68f2ff91512c1 Kees Cook 2021-04-20 501 const char *func)
a28a6e860c6cf2 Francis Laniel 2021-02-25 502 {
a28a6e860c6cf2 Francis Laniel 2021-02-25 503 if (__builtin_constant_p(size)) {
f68f2ff91512c1 Kees Cook 2021-04-20 504 /*
f68f2ff91512c1 Kees Cook 2021-04-20 505 * Length argument is a constant expression, so we
f68f2ff91512c1 Kees Cook 2021-04-20 506 * can perform compile-time bounds checking where
fa35198f39571b Kees Cook 2022-09-19 507 * buffer sizes are also known at compile time.
f68f2ff91512c1 Kees Cook 2021-04-20 508 */
f68f2ff91512c1 Kees Cook 2021-04-20 509
f68f2ff91512c1 Kees Cook 2021-04-20 510 /* Error when size is larger than enclosing struct. */
fa35198f39571b Kees Cook 2022-09-19 511 if (__compiletime_lessthan(p_size_field, p_size) &&
fa35198f39571b Kees Cook 2022-09-19 512 __compiletime_lessthan(p_size, size))
a28a6e860c6cf2 Francis Laniel 2021-02-25 513 __write_overflow();
fa35198f39571b Kees Cook 2022-09-19 514 if (__compiletime_lessthan(q_size_field, q_size) &&
fa35198f39571b Kees Cook 2022-09-19 515 __compiletime_lessthan(q_size, size))
a28a6e860c6cf2 Francis Laniel 2021-02-25 516 __read_overflow2();
f68f2ff91512c1 Kees Cook 2021-04-20 517
f68f2ff91512c1 Kees Cook 2021-04-20 518 /* Warn when write size argument larger than dest field. */
fa35198f39571b Kees Cook 2022-09-19 519 if (__compiletime_lessthan(p_size_field, size))
f68f2ff91512c1 Kees Cook 2021-04-20 @520 __write_overflow_field(p_size_field, size);
f68f2ff91512c1 Kees Cook 2021-04-20 521 /*
f68f2ff91512c1 Kees Cook 2021-04-20 522 * Warn for source field over-read when building with W=1
f68f2ff91512c1 Kees Cook 2021-04-20 523 * or when an over-write happened, so both can be fixed at
f68f2ff91512c1 Kees Cook 2021-04-20 524 * the same time.
f68f2ff91512c1 Kees Cook 2021-04-20 525 */
fa35198f39571b Kees Cook 2022-09-19 526 if ((IS_ENABLED(KBUILD_EXTRA_WARN1) ||
fa35198f39571b Kees Cook 2022-09-19 527 __compiletime_lessthan(p_size_field, size)) &&
fa35198f39571b Kees Cook 2022-09-19 528 __compiletime_lessthan(q_size_field, size))
f68f2ff91512c1 Kees Cook 2021-04-20 529 __read_overflow2_field(q_size_field, size);
a28a6e860c6cf2 Francis Laniel 2021-02-25 530 }
f68f2ff91512c1 Kees Cook 2021-04-20 531 /*
f68f2ff91512c1 Kees Cook 2021-04-20 532 * At this point, length argument may not be a constant expression,
f68f2ff91512c1 Kees Cook 2021-04-20 533 * so run-time bounds checking can be done where buffer sizes are
f68f2ff91512c1 Kees Cook 2021-04-20 534 * known. (This is not an "else" because the above checks may only
f68f2ff91512c1 Kees Cook 2021-04-20 535 * be compile-time warnings, and we want to still warn for run-time
f68f2ff91512c1 Kees Cook 2021-04-20 536 * overflows.)
f68f2ff91512c1 Kees Cook 2021-04-20 537 */
f68f2ff91512c1 Kees Cook 2021-04-20 538
f68f2ff91512c1 Kees Cook 2021-04-20 539 /*
f68f2ff91512c1 Kees Cook 2021-04-20 540 * Always stop accesses beyond the struct that contains the
f68f2ff91512c1 Kees Cook 2021-04-20 541 * field, when the buffer's remaining size is known.
311fb40aa0569a Kees Cook 2022-09-02 542 * (The SIZE_MAX test is to optimize away checks where the buffer
f68f2ff91512c1 Kees Cook 2021-04-20 543 * lengths are unknown.)
f68f2ff91512c1 Kees Cook 2021-04-20 544 */
311fb40aa0569a Kees Cook 2022-09-02 545 if ((p_size != SIZE_MAX && p_size < size) ||
311fb40aa0569a Kees Cook 2022-09-02 546 (q_size != SIZE_MAX && q_size < size))
f68f2ff91512c1 Kees Cook 2021-04-20 547 fortify_panic(func);
54d9469bc515dc Kees Cook 2021-06-24 548
54d9469bc515dc Kees Cook 2021-06-24 549 /*
54d9469bc515dc Kees Cook 2021-06-24 550 * Warn when writing beyond destination field size.
54d9469bc515dc Kees Cook 2021-06-24 551 *
54d9469bc515dc Kees Cook 2021-06-24 552 * We must ignore p_size_field == 0 for existing 0-element
54d9469bc515dc Kees Cook 2021-06-24 553 * fake flexible arrays, until they are all converted to
54d9469bc515dc Kees Cook 2021-06-24 554 * proper flexible arrays.
54d9469bc515dc Kees Cook 2021-06-24 555 *
9f7d69c5cd2390 Kees Cook 2022-09-19 556 * The implementation of __builtin_*object_size() behaves
54d9469bc515dc Kees Cook 2021-06-24 557 * like sizeof() when not directly referencing a flexible
54d9469bc515dc Kees Cook 2021-06-24 558 * array member, which means there will be many bounds checks
54d9469bc515dc Kees Cook 2021-06-24 559 * that will appear at run-time, without a way for them to be
54d9469bc515dc Kees Cook 2021-06-24 560 * detected at compile-time (as can be done when the destination
54d9469bc515dc Kees Cook 2021-06-24 561 * is specifically the flexible array member).
54d9469bc515dc Kees Cook 2021-06-24 562 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832
54d9469bc515dc Kees Cook 2021-06-24 563 */
54d9469bc515dc Kees Cook 2021-06-24 564 if (p_size_field != 0 && p_size_field != SIZE_MAX &&
54d9469bc515dc Kees Cook 2021-06-24 565 p_size != p_size_field && p_size_field < size)
54d9469bc515dc Kees Cook 2021-06-24 566 return true;
54d9469bc515dc Kees Cook 2021-06-24 567
54d9469bc515dc Kees Cook 2021-06-24 568 return false;
a28a6e860c6cf2 Francis Laniel 2021-02-25 569 }
a28a6e860c6cf2 Francis Laniel 2021-02-25 570

:::::: The code at line 520 was first introduced by commit
:::::: f68f2ff91512c199ec24883001245912afc17873 fortify: Detect struct member overflows in memcpy() at compile-time

:::::: TO: Kees Cook <keescook@xxxxxxxxxxxx>
:::::: CC: Kees Cook <keescook@xxxxxxxxxxxx>

--
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