user/sven/linux.git/scripts/Makefile.extrawarn, branch v6.16.2

Merge tag 'hardening-v6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2025-05-28T14:47:10Z

Pull hardening updates from Kees Cook: - Update overflow helpers to ease refactoring of on-stack flex array instances (Gustavo A. R. Silva, Kees Cook) - lkdtm: Use SLAB_NO_MERGE instead of constructors (Harry Yoo) - Simplify CONFIG_CC_HAS_COUNTED_BY (Jan Hendrik Farr) - Disable u64 usercopy KUnit test on 32-bit SPARC (Thomas Weißschuh) - Add missed designated initializers now exposed by fixed randstruct (Nathan Chancellor, Kees Cook) - Document compilers versions for __builtin_dynamic_object_size - Remove ARM_SSP_PER_TASK GCC plugin - Fix GCC plugin randstruct, add selftests, and restore COMPILE_TEST builds - Kbuild: induce full rebuilds when dependencies change with GCC plugins, the Clang sanitizer .scl file, or the randstruct seed. - Kbuild: Switch from -Wvla to -Wvla-larger-than=1 - Correct several __nonstring uses for -Wunterminated-string-initialization * tag 'hardening-v6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (23 commits) Revert "hardening: Disable GCC randstruct for COMPILE_TEST" lib/tests: randstruct: Add deep function pointer layout test lib/tests: Add randstruct KUnit test randstruct: gcc-plugin: Remove bogus void member net: qede: Initialize qede_ll_ops with designated initializer scsi: qedf: Use designated initializer for struct qed_fcoe_cb_ops md/bcache: Mark __nonstring look-up table integer-wrap: Force full rebuild when .scl file changes randstruct: Force full rebuild when seed changes gcc-plugins: Force full rebuild when plugins change kbuild: Switch from -Wvla to -Wvla-larger-than=1 hardening: simplify CONFIG_CC_HAS_COUNTED_BY overflow: Fix direct struct member initialization in _DEFINE_FLEX() kunit/overflow: Add tests for STACK_FLEX_ARRAY_SIZE() helper overflow: Add STACK_FLEX_ARRAY_SIZE() helper input/joystick: magellan: Mark __nonstring look-up table const watchdog: exar: Shorten identity name to fit correctly mod_devicetable: Enlarge the maximum platform_device_id name length overflow: Clarify expectations for getting DEFINE_FLEX variable sizes compiler_types: Identify compiler versions for __builtin_dynamic_object_size ...

Remove legacy 'cc-disable-warning' use from the generic build scripts

2025-05-27T21:40:30Z

This just converts the 'cc-disable-warning' uses in the generic makefile extrawarn script to use the plain 'cc-option' form instead. Partly to clean things up, and partly just to have the new form get some proper test coverage. I'll leave the various random other uses of 'cc-disable-warning' alone and let subsystem maintainers decide if they want to convert to the new unified model. Signed-off-by: Linus Torvalds

kbuild: Disable -Wdefault-const-init-unsafe

2025-05-12T06:03:17Z

A new on by default warning in clang [1] aims to flags instances where const variables without static or thread local storage or const members in aggregate types are not initialized because it can lead to an indeterminate value. This is quite noisy for the kernel due to instances originating from header files such as: drivers/gpu/drm/i915/gt/intel_ring.h:62:2: error: default initialization of an object of type 'typeof (ring->size)' (aka 'const unsigned int') leaves the object uninitialized [-Werror,-Wdefault-const-init-var-unsafe] 62 | typecheck(typeof(ring->size), next); | ^ include/linux/typecheck.h:10:9: note: expanded from macro 'typecheck' 10 | ({ type __dummy; \ | ^ include/net/ip.h:478:14: error: default initialization of an object of type 'typeof (rt->dst.expires)' (aka 'const unsigned long') leaves the object uninitialized [-Werror,-Wdefault-const-init-var-unsafe] 478 | if (mtu && time_before(jiffies, rt->dst.expires)) | ^ include/linux/jiffies.h:138:26: note: expanded from macro 'time_before' 138 | #define time_before(a,b) time_after(b,a) | ^ include/linux/jiffies.h:128:3: note: expanded from macro 'time_after' 128 | (typecheck(unsigned long, a) && \ | ^ include/linux/typecheck.h:11:12: note: expanded from macro 'typecheck' 11 | typeof(x) __dummy2; \ | ^ include/linux/list.h:409:27: warning: default initialization of an object of type 'union (unnamed union at include/linux/list.h:409:27)' with const member leaves the object uninitialized [-Wdefault-const-init-field-unsafe] 409 | struct list_head *next = smp_load_acquire(&head->next); | ^ include/asm-generic/barrier.h:176:29: note: expanded from macro 'smp_load_acquire' 176 | #define smp_load_acquire(p) __smp_load_acquire(p) | ^ arch/arm64/include/asm/barrier.h:164:59: note: expanded from macro '__smp_load_acquire' 164 | union { __unqual_scalar_typeof(*p) __val; char __c[1]; } __u; \ | ^ include/linux/list.h:409:27: note: member '__val' declared 'const' here crypto/scatterwalk.c:66:22: error: default initialization of an object of type 'struct scatter_walk' with const member leaves the object uninitialized [-Werror,-Wdefault-const-init-field-unsafe] 66 | struct scatter_walk walk; | ^ include/crypto/algapi.h:112:15: note: member 'addr' declared 'const' here 112 | void *const addr; | ^ fs/hugetlbfs/inode.c:733:24: error: default initialization of an object of type 'struct vm_area_struct' with const member leaves the object uninitialized [-Werror,-Wdefault-const-init-field-unsafe] 733 | struct vm_area_struct pseudo_vma; | ^ include/linux/mm_types.h:803:20: note: member 'vm_flags' declared 'const' here 803 | const vm_flags_t vm_flags; | ^ Silencing the instances from typecheck.h is difficult because '= {}' is not available in older but supported compilers and '= {0}' would cause warnings about a literal 0 being treated as NULL. While it might be possible to come up with a local hack to silence the warning for clang-21+, it may not be worth it since -Wuninitialized will still trigger if an uninitialized const variable is actually used. In all audited cases of the "field" variant of the warning, the members are either not used in the particular call path, modified through other means such as memset() / memcpy() because the containing object is not const, or are within a union with other non-const members. Since this warning does not appear to have a high signal to noise ratio, just disable it. Cc: stable@vger.kernel.org Link: https://github.com/llvm/llvm-project/commit/576161cb6069e2c7656a8ef530727a0f4aefff30 [1] Reported-by: Linux Kernel Functional Testing Closes: https://lore.kernel.org/CA+G9fYuNjKcxFKS_MKPRuga32XbndkLGcY-PVuoSwzv6VWbY=w@mail.gmail.com/ Reported-by: Marcus Seyfarth Closes: https://github.com/ClangBuiltLinux/linux/issues/2088 Signed-off-by: Nathan Chancellor Signed-off-by: Masahiro Yamada

kbuild: Switch from -Wvla to -Wvla-larger-than=1

2025-05-08T16:42:06Z

Variable Length Arrays (VLAs) on the stack must not be used in the kernel. Function parameter VLAs[1] should be usable, but -Wvla will warn for those. For example, this will produce a warning but it is not using a stack VLA: int something(size_t n, int array[n]) { ... Clang has no way yet to distinguish between the VLA types[2], so depend on GCC for now to keep stack VLAs out of the tree by using GCC's -Wvla-larger-than=N option (though GCC may split -Wvla similarly[3] to how Clang is planning to). While GCC 8+ supports -Wvla-larger-than, only 9+ supports ...=0[4], so use -Wvla-larger-than=1. Adjust mm/kasan/Makefile to remove it from CFLAGS (GCC <9 appears unable to disable the warning correctly[5]). The VLA usage in lib/test_ubsan.c was removed in commit 9d7ca61b1366 ("lib/test_ubsan.c: VLA no longer used in kernel") so the lib/Makefile disabling of VLA checking can be entirely removed. Link: https://en.cppreference.com/w/c/language/array [1] Link: https://github.com/llvm/llvm-project/issues/57098 [2] Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98217 [3] Link: https://lore.kernel.org/lkml/7780883c-0ac8-4aaa-b850-469e33b50672@linux.ibm.com/ [4] Link: https://lore.kernel.org/r/202505071331.4iOzqmuE-lkp@intel.com/ [5] Reviewed-by: Nathan Chancellor Reviewed-by: Christoph Hellwig Tested-by: Venkat Rao Bagalkote Link: https://lore.kernel.org/r/20250418213235.work.532-kees@kernel.org Signed-off-by: Kees Cook

kbuild: Properly disable -Wunterminated-string-initialization for clang

2025-05-01T01:57:56Z

Clang and GCC have different behaviors around disabling warnings included in -Wall and -Wextra and the order in which flags are specified, which is exposed by clang's new support for -Wunterminated-string-initialization. $ cat test.c const char foo[3] = "FOO"; const char bar[3] __attribute__((__nonstring__)) = "BAR"; $ clang -fsyntax-only -Wextra test.c test.c:1:21: warning: initializer-string for character array is too long, array size is 3 but initializer has size 4 (including the null terminating character); did you mean to use the 'nonstring' attribute? [-Wunterminated-string-initialization] 1 | const char foo[3] = "FOO"; | ^~~~~ $ clang -fsyntax-only -Wextra -Wno-unterminated-string-initialization test.c $ clang -fsyntax-only -Wno-unterminated-string-initialization -Wextra test.c test.c:1:21: warning: initializer-string for character array is too long, array size is 3 but initializer has size 4 (including the null terminating character); did you mean to use the 'nonstring' attribute? [-Wunterminated-string-initialization] 1 | const char foo[3] = "FOO"; | ^~~~~ $ gcc -fsyntax-only -Wextra test.c test.c:1:21: warning: initializer-string for array of ‘char’ truncates NUL terminator but destination lacks ‘nonstring’ attribute (4 chars into 3 available) [-Wunterminated-string-initialization] 1 | const char foo[3] = "FOO"; | ^~~~~ $ gcc -fsyntax-only -Wextra -Wno-unterminated-string-initialization test.c $ gcc -fsyntax-only -Wno-unterminated-string-initialization -Wextra test.c Move -Wextra up right below -Wall in Makefile.extrawarn to ensure these flags are at the beginning of the warning options list. Move the couple of warning options that have been added to the main Makefile since commit e88ca24319e4 ("kbuild: consolidate warning flags in scripts/Makefile.extrawarn") to scripts/Makefile.extrawarn after -Wall / -Wextra to ensure they get properly disabled for all compilers. Fixes: 9d7a0577c9db ("gcc-15: disable '-Wunterminated-string-initialization' entirely for now") Link: https://github.com/llvm/llvm-project/issues/10359 Signed-off-by: Nathan Chancellor Signed-off-by: Linus Torvalds

Fix mis-uses of 'cc-option' for warning disablement

2025-04-23T17:08:29Z

This was triggered by one of my mis-uses causing odd build warnings on sparc in linux-next, but while figuring out why the "obviously correct" use of cc-option caused such odd breakage, I found eight other cases of the same thing in the tree. The root cause is that 'cc-option' doesn't work for checking negative warning options (ie things like '-Wno-stringop-overflow') because gcc will silently accept options it doesn't recognize, and so 'cc-option' ends up thinking they are perfectly fine. And it all works, until you have a situation where _another_ warning is emitted. At that point the compiler will go "Hmm, maybe the user intended to disable this warning but used that wrong option that I didn't recognize", and generate a warning for the unrecognized negative option. Which explains why we have several cases of this in the tree: the 'cc-option' test really doesn't work for this situation, but most of the time it simply doesn't matter that ity doesn't work. The reason my recently added case caused problems on sparc was pointed out by Thomas Weißschuh: the sparc build had a previous explicit warning that then triggered the new one. I think the best fix for this would be to make 'cc-option' a bit smarter about this sitation, possibly by adding an intentional warning to the test case that then triggers the unrecognized option warning reliably. But the short-term fix is to replace 'cc-option' with an existing helper designed for this exact case: 'cc-disable-warning', which picks the negative warning but uses the positive form for testing the compiler support. Reported-by: Stephen Rothwell Link: https://lore.kernel.org/all/20250422204718.0b4e3f81@canb.auug.org.au/ Explained-by: Thomas Weißschuh Signed-off-by: Linus Torvalds

kbuild: move -fzero-init-padding-bits=all to the top-level Makefile

2025-03-15T12:19:44Z

The -fzero-init-padding-bits=all option is not a warning flag, so defining it in scripts/Makefile.extrawarn is inconsistent. Move it to the top-level Makefile for consistency. Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor Reviewed-by: Kees Cook

Merge tag 'kbuild-fixes-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2025-02-09T18:05:32Z

Pull Kbuild fixes from Masahiro Yamada: - Suppress false-positive -Wformat-{overflow,truncation}-non-kprintf warnings regardless of the W= option - Avoid CONFIG_TRIM_UNUSED_KSYMS dropping symbols passed to symbol_get() - Fix a build regression of the Debian linux-headers package * tag 'kbuild-fixes-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kbuild: install-extmod-build: add missing quotation marks for CC variable kbuild: fix misspelling in scripts/Makefile.lib kbuild: keep symbols for symbol_get() even with CONFIG_TRIM_UNUSED_KSYMS scripts/Makefile.extrawarn: Do not show clang's non-kprintf warnings at W=1

kbuild: Move -Wenum-enum-conversion to W=2

2025-02-08T03:49:07Z

-Wenum-enum-conversion was strengthened in clang-19 to warn for C, which caused the kernel to move it to W=1 in commit 75b5ab134bb5 ("kbuild: Move -Wenum-{compare-conditional,enum-conversion} into W=1") because there were numerous instances that would break builds with -Werror. Unfortunately, this is not a full solution, as more and more developers, subsystems, and distributors are building with W=1 as well, so they continue to see the numerous instances of this warning. Since the move to W=1, there have not been many new instances that have appeared through various build reports and the ones that have appeared seem to be following similar existing patterns, suggesting that most instances of this warning will not be real issues. The only alternatives for silencing this warning are adding casts (which is generally seen as an ugly practice) or refactoring the enums to macro defines or a unified enum (which may be undesirable because of type safety in other parts of the code). Move the warning to W=2, where warnings that occur frequently but may be relevant should reside. Cc: stable@vger.kernel.org Fixes: 75b5ab134bb5 ("kbuild: Move -Wenum-{compare-conditional,enum-conversion} into W=1") Link: https://lore.kernel.org/ZwRA9SOcOjjLJcpi@google.com/ Signed-off-by: Nathan Chancellor Acked-by: Arnd Bergmann Signed-off-by: Linus Torvalds

scripts/Makefile.extrawarn: Do not show clang's non-kprintf warnings at W=1

2025-02-05T15:58:02Z

Clang's -Wformat-overflow and -Wformat-truncation have chosen to check '%p' unlike GCC but it does not know about the kernel's pointer extensions in lib/vsprintf.c, so the developers split that part of the warning out for the kernel to disable because there will always be false positives. Commit 908dd508276d ("kbuild: enable -Wformat-truncation on clang") did disabled these warnings but only in a block that would be called when W=1 was not passed, so they would appear with W=1. Move the disabling of the non-kprintf warnings to a block that always runs so that they are never seen, regardless of warning level. Fixes: 908dd508276d ("kbuild: enable -Wformat-truncation on clang") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202501291646.VtwF98qd-lkp@intel.com/ Signed-off-by: Nathan Chancellor Signed-off-by: Masahiro Yamada